Slight updates from my card:
1) Heatsinks for the memory - up to you whether it's worth it, but as expected, they do very little. I got about an extra 50 Mhz from using heatsinks on them. Obviously you can only do this if you remove the stock cooler. Not sure if vMem mod helps, but I've killed a card from this before, so I'm too chicken to bother...
2) Core voltage - from what I can gather from my tests and the feedback from Xtremesystems, the voltage supply (of the card, not my PSU) isn't stable enough to the core at high clock speeds. Check this out:
Default (1.15 V) = ~1050 Mhz
1.25 V = ~1125 Mhz
1.30 V = ~1140 Mhz
1.35 V = ~1150 Mhz
I've not seen such poor response to voltage increases before and it's certainly not a temperature issue on the core (max I've seen is 38'C) or any other component (inspected all VRs / fets / whatever) and nothing is hot to the touch.
I'm not hardcore enough to do cap mods, so it'll have to stay as it is. Shame as I'd hoped for 50% increase = 1200 Mhz
Highest benches so far with various speeds on the CPU (up to 4.3 Ghz):
3DMark2001 = 66,732
3DMark2003 = 71,789
3DMark2005 = 26,413
3DMark2006 = 18,722
Just off to do some Vantage...
EDIT -
3DMarkVantage = 11,727
(CPU = 7664)
(GPU = 14,245)