I suppose the VL600 replaces both the VL710 and the VL900 as their doesn't appear to be a budget 5-device remote with full learning capabilities in Sony's product line-up anymore.

I've been using the VL600 for a little while now and it's an awesome remote. Great features and the build quality seems to be excellent. But if I were you I'd stick with the 900 ... especially if you can find one at the right price.

The 900 seems to be able to do everything the 600 can do plus a little bit more. For example, the 600 doesn't have the 900's glow-in-the-dark keypad or the dual key assignments (neither of which I'd miss). On the other hand, the 600 has more buttons. (This is where the 600 is always going to win out for me.)

Where I think the 900 seems to have the slight edge on the 600 is in terms of ergonomics. It has that nice tapered design with the most used keys within reach, and the system control keys up the top and out of the way where they should be. And the keys on the 900 are better spaced out and, according to the reviews anyway, are easily distinguishable to the touch. I don't find this to be so much the case with the 600.

Plus with a 900 you'll have the added advantage of being able to teach it your entire setup in one go from your existing remote. This feature has been dropped from the 600 (and also, I think, from the 710).