First off, for all these remotes I'll refer to Pronto as they all share similar hardware/software.
The RC5200 is not the same as the RU950 (that is the RC5400)
I have never had problems with the response time on the remotes (any of them) but then I don't know what you are comparing times to. All the codes I learn to the remote work just as fast as the original remote. It is faster in one way in that you only have to press one button on the Prontos to do something unlike the originals:- press, put down the remote, pick up the next remote press a button etc. All the actual codes can be sent for longer or shorter times by adjusting the IR length in the Pronto program.
All the Prontos have Vol+ Vol- Mute Chan+ Chan- hard buttons. Then on the older ones there are 2 buttons on the front, The newer ones have between 6 and 8 plus a 4way pad. The hard buttons are helpful to control items without having to look at the remote screen, especially as you get to learn where they are and you don't need to look. I found that you soon learn to make a layout that has the most popular macros assigned to hard buttons.
That you found price seems quite good for a "new" RC5200 (the RC5400 goes for around £350 - £400).
The contrast issue again depends on what you are comparing to. There are basically 3 versions of the Pronto style remotes. On the Prontos based around the old RC5200 (RU890, RU940, RC5000, RC5000i) you get a green screen with black (may be very, very dark green?) and 3 shades of “grey”. Unless you want to have really fancy designs for buttons, this works fine, especially if you stick to just black and mid grey. The back light makes it glow green and makes the buttons a little clearer. On the newer models based around the RC5400 (RU950) those have a lighter more turquoise colour and 16 shades from black to “white/grey”. The screen is definitely better and so is the backlight. Then you move onto the latest RC5400 and the RU960 which has an even better screen and better contrast. Finally you get the colour Prontos, and there are 3 versions of those too, with the screens getting better as they get newer.
The thing is, as far as the contrast goes. The old screens are just that – old screens and old technology. If money was not an issue you would go for the Pronto RU990 (Marantz RC9400) colour screen because you'd look at the other screens and think they are sh*t, but even the RU890 looks amazing to someone new to this! When I had my first Pronto RU940 last year it just looked amazing to me, but now I have the colour RU990 I can't think of going back!
Which ever you want and can afford is the way for YOU to go. You can always upgrade when you can afford better (and sell the old one to go twards the new). The contrast problems depend on what you are used to or have seen to compare!
Excuse the book I've just written
Stoobie