I'd say in real terms your H&D is worth more than the L32, but due to a couple of factors you probably haven't 'lost out'.
Firstly the fact that you're going to take it back to the USA where Avalons aren't easily available should claw you back a few dollars. Secondly the fact that Andy Mckee used an L32 on tour for a year or so seems to have increased interest in the L32 among 'wannabees', making them more desirable and therefore worth a tad more in the second hand market. Like him or not, he's certainly raised the profile of fingerstyle acoustic playing, and of certain handmade guitars
Regarding whether Avalon hold their value as well as Lowdens etc, i'd say at the moment they probably don't. There still seems to be a fair bit of snobbery around concerning Avalon and Lowden, I recently spoke to a luthier about having my guitars set up and was amused when his reaction to me telling him I had an Avalon was "Oh, those fake Lowdens?"
- It seems that some people can't take each guitar on it's own merit, needless to say I won't be taking my guitars to him!. I also think that some people view the fact that Avalon make/sell cheaper more mass produced guitars as a bad thing, somehow cheapening the brand name (this certainly is not my view, but it does seem to be some peoples!)
Ultimately though, if you like the guitar as much as (or more) than the H&D you swapped it for then the value is immaterial
I think once you've given yourself a bit of time to become accustomed to your new guitar, you'll be blown away by it, whether it's worth more than the H&D won't be an issue as the L32 won't be for sale
Enjoy the rest of your trip to the UK, and have a safe journey home with your Avalon!
EDIT - Ah, I see while I was typing, singlereed
made most of the points I was trying to make