Andrew - First step: read "Ready for a Speedster Replica? - (Everything you need to know)" posted in this forum, and most of the others.
Second step: Lurk on this forum for a while and read post after post.
Third step: Heed the warning that asking a question pitting one manufacturer's advocates against another has been known to start religeous wars on this site ;-)
Honestly, both vendors, as well as all of the others, have their good and bad points. I am (as you'd expect) biased toward the Beck because that's what I own. If you want to PM me for personal opinions I'd be glad to share them privately.
One of the best pieces of advice I've heard is to buy a used one first unless you are absolutely sure that a Speedster is what you want, and you're pretty sure how you want it configured. If you do that, you can live with your first one for a while before getting exactly what you want. Since there are more Vintages out there than any other brand, that's what most folks end up with at first.
Regarding your reliability question, remember that these are custom built cars, with parts from many suppliers, and therefore have many factors that will affect their reliability. Also, don't expect one of these to be as maintenance-free as a modern car. It ain't gonna happen. But that's one reason that we crazies love 'em so much - we like to work on our toys.
As for engines - the engine builder is more important than who you buy the car from. Neither Vintage nor Beck build engines. Beck gets most of theirs from CB Performance, one of the most reputable builders out there. I'm not sure who builds most Vintage engines, but you can specify the builder with each company, so it's your choice.
One of the worst things that you can do is jump into this hobby without adequate research. A fair number of folks do this, and you usually see their car for sale a year or two later with only a few hundred miles on them. Then again, you can pick up a bargain that way.
