A list of my why I personally like the R-1 (and perhaps why you'd like them too) and why I'm not currently interested in the Marantz models and the Microtrack:
-The size. Just because the MT is the size of a deck of cards doesn't make it anymore useful if now I also have to get a USB battery pack, and a stereo dual 1/4 inch to 1/8 adapter (to use the MT line in) just to make it work at minimal expectations. Sure, those additional things don't take up all that much space, but neither does the R-1. I had no problem crotching DAT, so this thing is an absolute breeze. And considering my rig is mics->homemade batt box->R-1 line in, I'm pretty much as light-traveling as I could get. Obviously the Marantz units are huge in comparison to either the R-1 or MT, and therefore not an option for me (and I suspect most of you who want something they can open tape AND stealth).
-Battery powered. It uses only two AA batteries and not an internal power supply. As has already been proven, the MT's battery life is questionable at best. And like I said before, internal power supplies have only so much time before they quit holding charge, which pretty much means you can only use the MT only so long over time before it will stop powering long enough to record a show of any length, which leaves you with having to have the internal battery replaced. Apple paid out big because their ipods weren't holding even half of the advertised juice. And already, people are resorting to hacking their ipods just so they can replace the battery themselves. That's nuts, especially since with a decent set of AA rechargeables you have easy-access power with the most minimal charge time. So, with the R-1, you can switch out batteries any time you want. And batteries are available at every grocery store and gas station in the country. And since it only uses two, any standard pack of four gives you two backup. I don't have the time to be worrying about "geez, did I charge the MT long enough? Am i ruining the charge cycle by not letting the battery completely run out? Will I have enough power?" It totally defeats the purpose of stealthing if I have to be checking the unit every ten minutes to make sure it hasn't died, not to mention waiting three+ hours for it to even charge each time I want to use it. This whole powering issue is one of those things that I have no idea where someone decided a "permanent" power supply was better than a removeable/replaceable one. If it's not broke....
-Easy layout and use. The R-1's button function is like a DAT or traditional walkman/stereo, so there's very little "re-adjusting" to be done. It has play/stop/volume/record/input buttons that are extremely easy to adapt to and are quick to set. Apart from the simple presets of your recording (bit rate, sample rate, stereo) there is no additional menu scrolling and click after click. In fact, the menu is as stripped down, intuitive, and as straight forward as can get, dare I say idiot-proof. To record, hit the record button twice, adjust levels, and then put the unit on Hold. Plus, the location of the input level button makes it so you don't have to worry about wrecking your levels after you put the recorder in your bag. It's hard enough to mess up even without tape over it. I give similar praise to the Hold button and power switch. An extremely well designed unit, button wise. Oh yeah, and for you people asking about the Value Wheel...it has nothing to do with your active recording. Once you have the Hold button on, it's frozen as well. And no, it isn't the input knob, it's just for scrolling the menu.
-The screen light. It's a dark orange/red that is much more stealthy IMHO than the bright blue light the MT has. Sure it's nit-picky, but it's a nice feature.
-The R-1 actually works, the MT does not. Half-working does not count. You don't buy a car that has an engine that doesn't start, but decide to get it anyway because the windows roll down now do you? There is no telling when the MT, if ever, will be working correctly. And by then, the R-1 can only have gotten better as well. Power issues appear to be the least of the MTs problems. And even if the MT was working, I still think the physical design of the R-1 is better. I'm all for more manual control and less menu scrolling.
-Last but not least, the R-1 sounds WONDERFUL. People on this board have already expressed that the R-1 is AT LEAST as good as mod sbm-1, and that's stock. Coupled with the fact that this unit works OUT OF BOX and is reliable, I am more than happy to stay in 24/44.1 for a long while. Time is money, and when there are shows to tape the last thing I need to be worrying about is whether or not my recorder is gonna let me down.