You'll get a LOT more that's on your checklist (you do have several of these, right?) if you go with a custom. Particularly if you want good numbers in terms of polars.
But like the man said, earlier in the thread, with your kind of $, get in touch with a couple of designers, & ask'em hard questions. Including what they'd budget for a build... and not just for a US based build mind you.
One aspect of going custom, is that you can decide where it's built. As well as how much of it by whom, & what parts
of it, are built where. Thus saving yourself a good bit of coin, even when factoring in the $ for a professional project
manager/skipper (AND Lloyds inspections at certain build checkpoints - a handy item to ensure quality, plus in terms of upping it's resale value).
The nice thing, once you've "finalized" your checklists (such are never really "done"), including your realistically, ideal polars. You can also run this info past both production builders, & those who build semi-custom boats also.
It'll quickly rule
out what obviously wont work, & a good number of maybe's too. But with other maybe's, it'll provide enough detail to put them in to either the keep, or discard pile. Given the costs of the changes you'd have to make to them, to get them to fit your criteria.
For more info on tuning your checklists, here are a few places to start. These sites have examples of what goes into doing the prelim's of what one wants in a custom boat.
A few can be found on Kurt Hughes
site, starting here:
Kurt Hughes Multihull Design - Catamarans and Trimarans for Cruising and Charter
& going to here Kurt Hughes Multihull Design - Catamarans and Trimarans for Cruising and Charter
amongst other places on his web page. That, & if you look @ the weights of his boats, vs. a production boat, it'll give you some ideas as to the why's on speed differences. And I've got some other empirical data on such, needs be.
Also, there's loads of good info on Eric Sponberg's site Articles
And snag it fast, as he's retiring by year's end.
Plus, if memory serves, John & Amanda Neal @ www.Mahina.com
have put together some foundational boat buying/design checklists also. Their resume's make them pretty qualified to hand out suggestions on this kind of thing.