I've ridden both - at the end of the day you've just got to think about what you want from a kite...

The Crossbow is a race kite - built for speed, high floaty jumps and general fastness...
The RPM is a freestyle crossover kite - Great for Freeriding, Surf & Freestyle (as per your 'style')...

You can unhook on the IDS bar - the Chicken loop gets a bit floppy at times, but it's definately possible. Check out the wakestyle boys on the 09 Switchblades - they're using the same bar...

The RPM bar works really well unhooked - no floppy bits, big chicken loop etc - and the RPM will fly much better unhooked...

The RPM's are now cheap as - In fact they are one of the cheapest big brand kites out there by a long shot @ $1784 (rrp) for a 12m - if you've got the slightest idea of unhooking in the future - go for the RPM...

If you want to get into course racing, or big old school boosts - board offs and such... Choose the Crossbow...