This is a very long post so I didn't read everything. I have seen some mentions of the guiding accuracy and as I have been using the AZ GTI extensively, I wanted to report that I can achieve up to 1"-1.3" over 400s when the sky is clear (and depending of the area of the sky you point to). It's overall an exceptional little mount capable of handling about 10 lbs of imaging rig (full frame DSLR, 300mm f2.8 lens, guide scope + guide camera). I have done guiding up to 10" at 500mm with good results. Everything needs of course to be properly polar aligned (I prefer PHD drift align over sharp cap... if I have time for setup) and balanced (it's a lot of weight for such a small mount).
A few other comments:
* it does have a lot of backlash, so if you can guide the DEC only north or turn it off, it's a good idea
* recently, I have had some drifting on the RA axis after slewing... it last for a few seconds (5-10s); possibly the consequence of extensive use with heavy equipments, but it's still rare and manageable
* only usable with guiding; if you want unguided, go for a skyguider pro; if you want goto, then go for CEM25.. but it's a lot heavier
The only other mount I could compare the AZ GTI to is the RST-135 (and travel crux). With the recent update of multi-star guiding, they do now perform much better than the AZ GTI and can handle impressive payloads (astrojedi is using the RST-135 with a c8 edged and without counterweight achieve 0.6-0.9 RMS... I am still baffled by that). But it's also 10x the price.
Summary for those portable mounts:
* if you don't want to bother with guiding -> skyguider pro
* if you are ok with guiding -> AZ GTI is the best mount I know of and is super affordable
* if paying 4k for a mount is not an issue, if you want extreme portability and you want to future proof for heavy equipment, the RST-135 or Travel Crux are your choice