Thanks very much for the interest and the advice. I will post my results, a description of how the session went and any conclusions I've reached.
Photomc, could you describe your semi-stand process for 1:100, please? Also what agitation do people generally use. (Once I've determined the exposure I may well do a second roll processed at 1:25, 1:50 and 1:100 with various agitation patterns.)
Also, what do you look for when comparing negs?
Thanks in advance,