My name is Victor Cheng and you referenced my article on work / lifestyle balance in your question.
Most career moves are motivated by a desire to reach a goal you have difficultly achieving without the move or to address some kind of problem or risk in your current situation (e.g., pending layoffs, etc...)
From your description, it doesn't sound like you have a high priority nor immediate problem with your current situation. There doesn't seem to be a strong reason to switch careers on the basis of addressing a problem.
In terms of your current goals, your current situation seems to get you pretty much everything it is you want. Consider yourself lucky. Again, you've already achieved your goal so why move?
There are a few scenarios, which I've seen play out negatively in other peoples careers in almost the exact identical situation, that you need to keep an eye on.
The main issue is does your current role keep your skills MARKETABLE to everyone else. If the product you know loses market share, and another product comes to dominate, you may be a leading expert in a product that is becoming obsolete.
This can potentially be a huge problem. I know someone who in the year 2000 was a very good Lotus Notes administrator - well paid, well respected, great lifestyle. The problem was around 2001 or so Microsoft Exchange was quickly overtaking Lotus Notes as the enterprise wide email and contact management system of choice.
From my perspective, the writing was on the wall. I encouraged this person to be proactive about this problem. He wasn't interested. He rode that wave for another 6 years or so. Then in 2007/2008, he got laid off due to a slowing economy. As he went to look for work, he had a rude awakening -- nobody needed system administrators for a system they didn't have. Lotus Notes was long since dead and he didn't know any other products. He has been unemployed for well over 4 years.
The advantage of working in a consulting firm, particularly in a technology field, is you get more opportunities to learn new technologies, keep current, and to make sure your skills never get obsolete. Your learning options is driven by the market overall, not just the quirks of a single employer.
If your employers technology choices map the rest of the industry, then it's probably not a problem. If they diverge from the rest of the industry, either now or in the future, that IS very much a problem.
Another scenario to consider are the future incomes needs of your family. If you live comfortably, aren't planning to have more kids (with associated increase in expenses) and live within your means, this may not be an issue. If you see bigger bills in your future, then you have a personal preference tradeoff decision to make. You need to decide which is more important.
Unlike the previous example where's its definitely wrong to stay on a career path that's becoming obsolete, deciding to be on one end of the [earn more + work more] vs [earn less + work less] is merely personal preference.
There is a final scenario that's related to the one I just mentioned. You should keep in mind that your preference may change over time. You want to consider the "optionality" of each career option.
A simple test of optionality is if you are currently in Job A, and switch to Job B, do you have the option to come back to Job A in the future? Similarly, if you stay in Job A, declining Job B, do you have the option to pursue Job B at a later date?
Another way to consider optionality is via the concept of "windows of opportunity". Some windows of opportunity last a long time -- years. Others much less.
Options are useful because it gives you the option, but not the obligation, to benefit from a career choice that you have not yet taken. So by staing in your current role, so long as your skills stay current, you always have the option to change your mind later.
Conversely, if you stayed in your current job and your skills slowly became obsolete, you would lose the option to move to job B (consulting) because at some point in the future they no longer want your skills.
You want to consider 1) what options you have and 2) the length of the window of opportunit you that option. When #2 shrinks, it makes sense to move proactively well in advanced of any actual consequence.
Good luck on your decision
PS. My example of work life balance in strategy consulting is typically more extreme than what you would likely experience in IT consulting. The main driver of good or bad lifestyle in consulting is whether or not your clients are local or out of town. If you work a 35 hour week, but to get home you have to fly on an airplane, the hours are irrelevant as you're not at home 4 days a week.
If cliens are local, which would be a good thing, given your goals, then it is a function of firm culture and client expectations. Investment banking clients expect all their vendors to work long hours like they do. Commercial banks where all employees go home at say 5pm never want to have a meeting with you at 5:15pm.
You also want to consider the billing model of the firm. Are they billing by the hour (in which case their incentive is to work you hard as they make more money) or do they bill you by the day or week -- in which case it is the severity if any deadlines that drives whether you're working hard or not.
Finally, be careful what people say the lifestyle is like. Better to just ask them what time did you get in the office yesterday? What time did you leave?
Also if days are longer, consider whether the longer hours are skewed in the AM, PM or are flexible. For my family, if my kids don't see me for breakfast they don't really care that much. All I'm doing in the morning is "processing" them - making lunch, making sure they didn't forget their hat, hustling to get them to school on time, etc... It's all necessary stuff, but nobody is really have a good time.
However, dinner and bed time is when play, connect, confide, etc... That's our quality time. So if I had to work longer hours, I prefer longer EARLY hours to longer LATE hours. So keep in mind not all hours are created equally. You might want to consider this nuance as well.