I like the 125 form factor. Even the small screen (if the same as the 125) would easier to read with my old eyes than the 436 (it needs a brighter back-light), though the 16 char alpha tag limit would be hard to go back to.
I'd like to know what the limits are for the dynamic memory (channels, groups, systems, etc.). I'm guessing they are similar to the 996XT or the 396XT. I found those limits to be problematic with some of the systems I like to listen to; have been spoiled by the lack of real limits in the HP series.
Most importantly, I'd like to know how this scanner works with P-25 Simulcast systems. The County in which I live switched over to a Simulcast system last year. Simulcast systems are becoming common place (or certainly will be in the near future) in metropolitan areas across the State of Ohio (and I'm pretty sure much of the country). If it can't handle Simulcast systems at least as well as the BCD436HP, it will have limited utility.