I'm not one of the resident gurus, but I've been looking at both of these remotes and even as a URC fan I decided to give the 700 a shot.
1) You can get the R50 considerably cheaper on Amazon (Authorized dealer and $85), while both are currently about the same price in stores. Best Buy has the 700 on sale for $119, making it I believe $10 cheaper, although that price probably expires today.
2) I wouldn't be too concerned here. I have an old Yamaha Receiver, U-verse (Bleh), a Panasonic Plasma, a Panasonic BluRay player, a very old Sony VCR and etc... no problems with the 700, and I doubt you would have trouble with the R50. URC has an awesome code database. My old MX-500 worked just fine with all of the above, except U-verse because of the new un-learnable codes it uses.
My only gripe here was that it lacked some discrete codes for newer equipment, like the TV and BluRay player. As the R50 is cannot be updated by the consumer, it's likely that would happen in the future, but it's hardly crippling. You simply must teach any missing codes to the R50. Getting discrete codes may require that you get something like a cheap JP1 remote - load the code into the JP1 programmable remote and teach it to the R50.
3) The 700 had discrete codes for everything that has that ability. U-Verse doesn't support this, so it's the one problem child (just one of many reasons I regret switching to U-verse.) (e.g. My TV has an "Off" code and "On" Code, plus HDMI1, HDMI2, HDMI3, etc...; U-verse only has On/Off Toggle.) The R50 would likely have discrete codes for everything from before the day it was manufactured, but as mentioned you can teach it missing codes.
With Harmony remotes, macros are incredibly easy to setup, however you are very limited in the customizations you can do. I haven't found a problem with that yet, since you can add specific items (e.g. I have it send "2 Channel Stereo" to my receiver when switching to music of any kind.) You simply cannot edit macros step by step.
With the URC remotes, you build the macros essentially by walking through the steps. i.e. You start out by going to the TV device, push "ON", push "HDMI 1", go to A/V Receiver, push "On", "HDMI1", and so on. The problem comes when you realize you want to power everything on first (faster macros that way.) To change it, you have to do it from scratch. It's not horribly difficult, but it is sometimes best to plan what you're going to do. Of course, if you're one of those that doesn't mind that everything turns on at once, it's incredibly simple.
4) Neither of these has touch screens. The R50 appears to have a better screen, but I have not actually used it. The screen on the 700 is alright. It displays 4 items, and you can fit quite a lot of descriptive text on each... it simply wraps and shrinks. My guess is the R50 is considerably better here, though I think it is more limited in text.
One of the things I'm not sure I like on the 700 is the Activity "hard buttons." You have "Watch TV", "Watch Movie", "Listen to Music" and "More Activities" above the LCD and these are really the only buttons on the hold remote that are not backlit. For some reason, that really bothers me. You are also limited in the number of soft buttons (i.e. 4 vs. 6 on the R50.) I'm used to having 10 on the MX-500. You have far more pages to put buttons on, and you simply have to scroll through them, but more were immediately available on the MX-500. The 700 just feels cramped. Fortunately, you have far more freedom to move buttons around very easily. On the stand-alone URC remotes, you generally have to resort to sending the code to another learning remote and then learn it back on the desired button.
Other things perhaps worth noting... the IR strength of the 700 is very average and it feels cheap to me. The more I use it, the more mushy it feels. I looked at the Harmony One today and it feels considerably better. I'm also not a big fan of rechargeable batteries - personal preference, but I'd rather change batteries every 4-6 months than charge every few weeks. The 700 also has no cradle and charges via it's USB port. It also only supports 6 devices vs. 18 on the R50.
The Harmony remotes also tout the "State Monitoring", where it tracks what it does, and if something didn't go quite right, you simply press help and it tries again. If it still didn't work, it walks through questions until it is all fixed. It's somewhat nice, but if you have discrete codes for everything, all you really need to do is go fire the macro off again. It's usually the U-verse receiver for us, so in the case of the R50, firing the macro off again would simply send another on/off toggle and likely turn it on.
The URC R50 is most definitely a better remote, but it's handicaps are what are keeping me away from it right now. I put a lot of time into programming my MX-500 and I don't see the R50 being a lot better (but I'm picky.) At the same time, I flip back and forth and figure I could pick up a cheap JP1 remote and cable, plus the $85 R50, for about the same price (likely less) than the 700. That gives you the longevity of the 700, without the reliance on Logitech to update it or add codes, and a much higher quality remote.
