oy vey - let me see if I can get the dead horse pushed over to the side here and answer (briefly) the question.
DISCLAIMER - I have never driven or used Revo. I don't care about the previous legal action between them (APR alleged that Revo stole their software years ago, sued, blah, blah, blah). Both are very legitimate companies with plenty of followers in both camps. And you have to be willing to pay to play. That is, in the real world, if you break something on your car related to your powertrain mod, then you have to be prepared and able to cover any expenses relating to that. No whining about "I'll just throw it into stock mode and make the dealer fix my grenaded clutch" or such silliness. Now, if a window regulator craps out then yes, VW should fix it 'cause that has nothing to do with allowing more boost from your turbo.
To probably oversimplify, the general consensus is that APR allows increases in stock boost levels from 1 bar to roughly 1.35 bar (approx 15 psi to 18.5 psi) and remaps so that you can hold boost longer into the powerband. Revo does exactly the same thing with allegedly a little more boost into 1.5 BAR territory. I have no technical proof for any of that. APR uses ECMS (cruise control switches) to control which program you want, security lockouts, etc. Revo does this via a dongle which plugs into your OBDII port.
I just got APR stage I on my 2010 GTI tonight. I tell you what - it is smooth, actually has better throttle response than stock and once you get into the fun zone (say 3,800 rpm and further up) it definitely pulls like a mofo compared to stock. The dyno runs say we run out of turbo at 6K so I was shifting there and you're definitely into "more than enough power for street use" there.
The sale was too good to pass up and honestly, I think the anti-theft feature and the "clear fault codes" ability along with improved gas mileage would probably justify the $600 right there on the sale price. Obviously, most of us (me definitely) get it for the performance increase and the other stuff is just icing on the cake. Someone once said "go get whatever dealer is closest to you" and that might be pretty good advice as well! But IMHO, based on reputation, free reflashing if needed, no dongle or hardware required and NGP being 30 miles from me, I went with APR. FTW as far as I'm concerned. I'll let you know how she's holding up after 50K or 60K miles!