"I tried to get an RA. The difference is greater than I expected. Just need to get familiar with it. It is so light, I suspect I could probably have got an 82 or pos 90 & still noticed a significant difference to the RA90. 25mm might be the future."
That's a classic:
Back to the future! 
Formerly, most euro band-guns had a 25mm alu barrel. This barrel diameter was - IMO erroneously - almost entirely abandoned by manufacturers in the early 80s when the band performance significantly increased and the issue of barrel flex became more important, but not much of an issue on a 75cm arbalete.
Cheers, ulysses