We are both solution architects and fairly new at a company. This project is not related to our direct work but an initiative that involves the wider department. My colleague invited me to co-lead an internal side project, the idea in essence is great.
Our approach is very different; they want to be more agile and iterative, whilst I want to plan ahead. We also disagree on who can participate; where I am more flexible/ collaborative whilst they aren't. You get the gist...
I have communicated and articulated my concerns and suggested how we could find a middle ground (even get informal advise from our peers on how they can get the most value from the project). On a separate note, I don't envision the project would go well in the longer run and don't want to be associated with it as a lead, with the current approach.
What is the best course of action to take and not let my biases get in the way?
At this point, I intend to suggest (one last time) doing a pilot with their approach. If there is a lot of resistance from my colleague to even that, then step down as a "lead" as this would take a lot of my time and energy in the long term.
Is this unprofessional?