Rescuer - There was a new Australian racing day yacht launched a couple of years ago that was extrememly well reviewed I thought it was called the J3000 or some such but a search hasn't come up with anything. I'll trawl back through my (el saddo) large collection of Yachting Monthlys when I have a chance. I recall it was about 30' for c.£30k and I also recall salivating over it at the time.
No, in theory a well built boat should not depreciate over time as long is it is fairly maintained. I had my boat valued at 52 - 56k this year and the original bill of sale back in 1989 was for £53,511 but the equivalent boat new today would probably cost about £120k
If you buy new you might "lose the Vat" but that is about it. The only variation to that is if a design is seen to be outdated, for example in cruising yachts good sea berths used to be very important, ie something akin to a bread bin that you could slide yourself into without fear of being tossed out of on a night crossing of the North Sea when your helmsman takes a short cut through a rough patch. These days wives have considerable more say on the purchase and large aft double cabins with vanity mirrors (strewth) will be on display in abundance at Excel. Hence older designs are less popular as they are not currently in vogue! Before you buy anything check out comparatives on and remember there are a hell of a lot of second hand boats out there and they can be a lot easier to buy than sell!