I have had the last 5 cars mapped by Revo and have yet to use my SPS, you can usually negotiate a free one of these anyway, try talking to Revo HQ and see if any promo's coming up.
I have used Bluefin and all versions of GIAC but for me Revo does exactly what it says on the tin, each and every time, you get what you pay for I guess ?!?
In regard to Milltek, I have also used these extensively for everything from S3, TTS, BMW 130, Golf GTi Mk6 and despite a couple of very minor issues which were sorted very quickly I have to say the quality is spot on and my use has been very extreme with frequent track days so all in all very pleased.