I just got a new drysuit from Ravenspring in England (I'm in the US). The only glitch was that the attached neoprene socks were rather too large, but they promptly sent me another pair to replace them. The noteworthy bit is that their seals are heat activated, and remove and replace with the heat from a hair dryer. Now I have not actually tried the replacement yet so I don't have direct experience with this method, but it does seem rather more straightforward than messing with aqua seal etc.

I haven't even had the chance to do more than just try on the suit, but so far I am more than satisfied with it and with Ravenspring. The seals themselves seem to be somewhat thicker and more comfortable than the ones I have seen in the US. My opinion may change after an extended period of wear, but first impressions are very good. They do sell the seals separately, and mail order delivery from the UK has been faster than a lot of domestic shipments.