I don't think we're far apart on much of this, although like you said I think the differences are optimal mitigation and for me, sovereign accountability and transparency. Without the latter you're missing a vital cornerstone of real democracy.
The other big issue for me is where the EU is heading. It's OK voting for Remain and saying Leavers don't know what they voted for (I'm not levelling that at you, more as a general observation of arguments I've heard) but in reality, Remainers don't really know what they are voting for either... the EU is not a static project - it's moving toward a Federal Superstate and all the pillars that go with it. Federal Superstates of different cultures, languages and values are doomed to fail. History tells us this over and over again.
A multi-tiered multi-speed Europe might work but the direction it's currently going won't. The Eurozone will likely implode in its current format (only a matter of time IMO), the EU executives ignorance of local concerns and a growing culture of blaming the EU for everything will permeate into the rise of far left and far right groups all around the continent.
I don't think the EU has been bad for the UK to date. I don't hate the EU, just some of its structures and the direction it's heading. On the contrary, I think from the early 80s through to the GFC was a period where you can say This is as good as it gets... despite people moaning 24/7. But I think we're entering a different time and the UK will be better served by being out than in to deal with it, and to plot its own course.