What comes to mind as an R1 owner:
Will Oade mods be available?
Will auto file splitting be a feature added with a firmware update?
Is the ADC of the same quality as the R1?
How easy is it to set levels accurately in a stealth situation?
Now, what tapers who aren't stealthing should consider:
No, 24/96 support and 2gb file limits (which means you're going to run into situations where you will lose a second or 2 during a long set)
No digital inputs (but if you don't own a V3 or digi-mod UA5 this doesn't matter)
Possible issues with metering accuracy
No idea on battery life as of yet
Now a couple other thoughts come to mind. Since the MT digi inputs don't even work yet, having a single 1/8" input is better than having to use an interconnect dongle to plug your signal into the recorder (lo-z 1/4" lines are unbalanced, just like 1/8" so there's no advantage to those on the MT). Those who are open taping and don't have a digi-mod UA5 or V3 may want to just go with the R4 instead of any of the other units out there. The ability to record at 24/96 to a HARD DISK and also supply power to 4 mics on BALANCED inputs kicks any of the other portable recorders asses (except for the 722/744 of course). Sure, the price of the R4 is a bit higher than the R1/MT/R9 but you don't have to purchase flash cards (at $200+ for 4gb) which brings any of the cheaper options up to around 500-700 depending on options. Also, with the R4 you don't need an external pre - so you can sell your V2/Minime/UA5/whatever and just use the internals and pay for the recorder with the pre. The only real downside for the R4 seems to be some issues with powering but I'm not sure how true that claim is since there are folks who run the units regularly. Being an R1 owner, I really don't see anything being better except for the R4 or 722 as far as compact field recorders go. If the R9 works and sounds as good as the R1 though, it would probably be a better buy than the R1 (and more stealthy also).
So, buy an R4 is you're open taping and want 24 bit recording but can't afford a 722. If you're stealthing and the ADC is comparable to the R1, sell your MT and buy the R9.
...that's some stream of thought so maybe it's a bit sloppy, sorry.