I've owned both an R09 and an M10. The R09 isn't bad but considering it's a 4-year old product, I'd strongly considert the M10.
The R09 had issues, as a few people have mentioned, with "input jack woes" as it was put - essentially, too much stress on the jack caused it to lose an internal connection leading to shorts, etc. I never experienced this. The R09 did a good job for me when I used it from 2008-2011. The R09 is listed an a 24/48 recorder, however, you can enable 24/96 on it through a service menu using the most recent firmware (the link is somewhere on these boards). The R09 has a louder "noise floor" when tests have been run on it. Honestly, if you're using it with mics, you're never gonna notice this.
The R09HR is essentially an "updated" R09 with 24/96 capabilities and a quieter noise floor.
I had the chance to use my buddy's M10 for a show I rolled on back in April and must admit it was worth the money. For $220 from B&H, it's a bargain. I found the screen easier to read and the battery life on it is absolutely sick. I did some tests (as have others) and found I could get about 23-24 hours using older Eneloops with my battery box and card mics (that was on ONE charge). The M10 has 4GB of internal memory so if you should ever run out on your memory card, you can tell the recorder to either automatically switch to the internal when the card is full or do it yourself. When used with an external pre-amp, the M10 doesn't have to be "gained up" as much. I found with the R09, even though unity is Line Input Level 13, I'd often have to gain up on the deck because I was pushing 80% gain on the preamp. With the M10, I could set the deck at just over 5 (deemed unity by the community) and run the pre-amp around 12-1 which is where it should be. The M10 is my choice of the three even if you can get one of the others used for $100-or-so. I've read of issues with te R09 and R09HR not waing up out of "powered off" / "hold" mode -- this is where you have the deck in hold while off (to save the batteries) and take hold off and it won't power up; the only the way to get around this s to do a battery pull. That happened to me once.