Ah, I knew they weren't the same but didn't realise piston sizes were the only difference. Pistons larger on SP1's will give slightly more lever travel I guess, but there won't be a lot of difference I'd expect.
So I'd be up for a set of SP1 or SP2 calipers then...
I see them for sale here from time to time, but thought I'd ask on here first. Any SP2 calipers kicking around?
Euro RC51 SP2: HRC WSB Ti Hi-Level, T1 Airbox & Snorkel, PCIII, Dymag CA5 Carbon Wheels, Ti64 Spindles (F, R & Swing Arm), Mori Link, Maxton GP7 Shock & Ohlins 832 Forks, Brembo GP Calipers & SBK narrow track (F), Braketech Disc (R), Brembo billet Underslung x 2 Brembo RCS, Tyga Triple, 7075 Stem, Probolt Titanium all over, Babyface rearsets, MR Complete Carbon Lineup, Custom Undertail & CBR 1000 LED, Watsen LED Indicators, Harris Brace, Giles clip-ons, Corbin seat, etc. 2013 BOTY.