The bottom line is that non-technical people should have no say in an issue that is purely technical. This is technocratic democracy and it's simply the best way. All technical people should be invited to the discussion and then they can vote amongst themselves, simple as that. Then the results are made public and the miners will upgrade based on that, if the team decided to go forward with either BIP. There should of course be a vote for "neither".
If this issue is handled in any other way, I will seriously lose confidence in Bitcoin. The public debates need to end, they are not helping to solve the issue, instead they are just adding doubt in people's minds.
In theory, what you say looks "ok". However, in practice, things are a bit different.
You are drawing a thin line between 'democracy' and 'dictatorship', thus the 'technocratic' loses its importance.
I do agree with what you said about the public debates, though. And I believe that, more than doubt, it can shift the voting based on something other than the technical issues:
This has moved from a pure decision between BIPs to a 'quarrel in the arena' between Luke and Gavin. I realized that when one day I woke up and just saw Luke campaigning in #p2pool.
And what happens then is that people will make decisions based on their personalities more than on the 'quality' of their technical arguments.
I can clearly see thoughts like "I don't know Candidate number 2, but I know Candidate number 1 is a fanatical religious zealot, so I'm voting for 2". (*1)
Albeit inevitable, certainly not good for Bitcoin as a whole.
(*1) Just a fictional example. Or maybe not.