Waiting for the new sprag clutch to arrive , gave me some time to read whatever I could find on starting strategies .
Also did some stats on the data I logged from a couple of hundred starts (spinning the phonic wheel) with the WM ECU .
Came up with a series of maps to test .
Tossed this aside and tried a banzai approach

a) Reduced the sensor to wheel clearance to .5 mm
The Guzzi sensor sees the tip of the tooth , the Duc one sees the flanks .
b) Swaped the harness wires to the injectors .
Though the ign coil wires for the Guzzi and Duc match - obviouslly- Right cyl to Front and Left to Rear , the injector wires don't . Right cyl to Rear and Left to Front ( for the 2002 900SSie at least ) ---> messed up injection timing .
c) Set first rpm breakpoint to 300 rpm
Seems like the WM ecu fires the injectors at prime values for only a very sort time (0.2s ?) during starting , and above 300rpm uses the maps for inj and ign .
d) Filled the 300 rpm collumn with the injdur values from the logged data (roughly "idle + 50%") .
e) Set Prime and Crank Boost to ridiculisly low values - no way the bike would start .
I then started increasing Prime until it fired - it would die soon after .
Increasing Crank Boost 5% each step , I managed to bring it to idle
If , during C/B , rpm rise slowly to idle , it's too rich .
If they slowlly fall , it's too lean .( not my findings these )
Did this for 10 to 80C .
At 10-30C I use no throttle (engine spins faster / better gas evaporation due to stronger vaccum ) untill it fires , then just a bit of tps .
Over 30C , no throttle at all .
No backfires , starts every time

I only noticed a couple of b/fs when using throttle from cold

I'll ride the bike some and then try to find out the changes that made the most improvement .
Cheers all