Having followed another thread (Processing version 2010 vs 2003) since posting my question, it looks like our assumptions are on the right track.
Most of all i want improved image quality, and as always, improved performance would also be nice, so i'd happily live with re-doing work on older images if it improves them.
Naturally it'd be really nice if basic editing - spotting, colour corrections, and most localised editing etc remained good for the new '2010 pipeline'.
Reading between the lines, it looks like that will be the case, with the main areas that will need 'revision' being confined to sharpening and noise reduction.
I have not looked at the Beta, as it takes me so long to get to grips with new software: back to work in LR2.6 for now, and very much looking forward to the final release of LR3.
Thanks,
Scott