I just thought I'd try and be helpful to the group and report a success update to my original post
http://www.buellxb.com/Buell-XB-Foru...-2-3-rpm-again

I got a significant improvement to the surging issue from the list of mods below:

Standard exhaust valve zip-tied open
Breather re-route (2:1 exiting front without catch-can/filter)
All grounds cleaned and tightened
Additional ground wire (coils to battery negative)
ECM repositioned
TPS reset
Inlet leak checked (butane and WD40 methods) - seems ok
Stock air filter changed to K&N
Use of fuel system cleaner - Tunap 173 micro logic (recommended by my local bike mechanic)

I think the final piece was finding a carb/fuel cleaner that actually works - then letting the bike learn from all the mods. And also letting the engine warm up for a few minutes before riding.

The bike changed from being dangerous and annoying to ride - so much so that I would have got rid of it!!!
Now the bike is a little lumpy at 1900rpm (no surprise eh?) and also at 2,900rpm as it switches between open and closed loop.

Now I think this a fantastic bike which puts the biggest grin on my face every time I ride it :-)

Many thanks to all the group for helping me solve it!!!