Hi Jrcosmo,
I've got the ProAc D15, and tried various options including using a carpet tile below each speaker (I've got ceremic floors so the supplied spikes would have caused some damage on the flooring) and finally settled on something called Soundcare superspikes. Checkout the website.
http://www.soundcare.no/
Another option you could look at is to get Symposium Acoustic svelte speaker platforms.
http://www.symposiumusa.com/svelte.html
BTW, did you manage to compare between the D15 and D25 when you were at the dealer, I got the ProAc's when it was introduced in 2002 so there wasn't a chance for the comparison.