Finally got my new tyres fitted by Wheels Around and have to say that they are highly recommended. They managed to get 5 of my stuck bolts off and drilled the other 3 out, putting in a lot of time and effort to do it when other places would've (and did) fobbed me off.
Anyway, drove home in the pi$$ing rain and gales on Monday night and it was the most nervous I've been in the car. Elise + standing water + tyres with releasing agent = bad. However, the Yokos coped remarkably well even with the larger puddles that I hit. Having now driven them on slightly drier roads, I instantly found them less squishy than T1-Rs and fairly grippy even though they're not scrubbed in yet.
Roll on the '06 trackday season and here's hoping for some decent dry weekends soon.