I also had a Rainbow, and had the same "problems" you described - as a result, I never got the warm fuzzies with it either.

If you're dead sold on the Tarptent products, ignore the rest of this (and I apologize; my intent is not to hijack the thread or leave the impression that Tarptent is not a top-notch tent choice.) If I were choosing one of the two, I'd choose the Rainbow; I like the convenience of the side entry, the ability to sleep with my head at either end, and the option to make it freestanding if necessary. I've owned a Rainbow, briefly, and found nothing inherent about the tent that made me decide against using it as my primary tent.

However: I see you're from Maryland; I'm from Ohio. I also notice that ventilation is a big deal on your list - it is a top priority for me, too, in the hot, humid summers you and I hike in. For that reason, and that reason only, I ended up choosing an MSR Hubba (and eventually Carbon Reflex 1) instead of the Rainbow as my tent: the MSR tents are 99% mesh, if you don't put the fly on, and you can't ventilate any better than that. You don't have a choice to leave the fly off the Rainbow. As a result, in the 90-degree, 90% humidity August conditions I encounter, I found that, even with the vestibule and all other venting totally open, the Rainbow still got warmer than the outside air. The Hubba/CR1 without the fly didn't.

Now, if you need the fly, the MSR tents are just as stuffy as the Tarptent. But, if it's necessary to add the fly, you'll have both tents pretty fully buttoned up (because it's raining.)

Just a thought about ventilation. Other than that one issue, and the PITA issues you described, I found the Tarptent Rainbow to be high-quality, roomy, and comfortable. If I were hiking in less humid conditions, I'd absolutely get one. I really thought that integrating hiking poles to make it freestanding was design genius - so much so, that I stole the idea and use it to make my CR1 freestanding when necessary. (MSR didn't add the convenient attachment points for this, but it's easy to improvise them with some cord.)