Hey Fred,
I've been mulling over the same thing as you recently. I have both a 4x5(sinar F2) and 8x10(old burke and James).
both have their uses. I shoot easily 10x more 4x5 than 8x10, just due to portability issues, and most of the time, 4x5 meets my res. needs perfectly fine.
I started with 4x5, but personally, I wish it had been with 8x10. Looking at an 8x10 ground glass is an experience that is like no other, well, maybe 11x14 .
since you're shooting 90% B&W, the efke films are great! And very cost effective too! Like, $32 U.S. for a 50sht box from Freestyle. I shoot the 25 speed stuff, since its EXTREMELY fine-grained, and has that 'old-school' feel to it.
I'm at home with my folks while at school, so the 2nd bathroom doubles as my "darkroom". I haven't been able to get up and running yet with printing(contact printing only), but so far, developing film has been no problem whatsoever.
5x7 is a great format, I've only shot it once, but it was a very nice format, and I can see why some people use it as their primary format.
8x10, to me; is the end-all of formats. It is *just* portable enough, without being HUGE, but 4x5/5x7 kicks its butt in the portability game.
don't let people tell you off that 4x5 or 5x7 is too small to contact print, bollocks. Just cause some people think that a decent print is a big print, they're full of shite IMO. Big pictures are great in some cases, but you run out of storage space REALLY QUICK! 8x10 is big enough to let you see SUPER FINE DETAILS(think individual hairs in a portrait), but sometimes a 4x5 or 5x7 contact print is more 'intimate' than a big-ass print. Brings the viewer in closer too.
look at this website, its CONTACT PRINTING ONLY, it'll knock your socks off!
www.michaelandpaula.comthey work in silver-chloride, not silver bromide(traditional papers), and their darkroom consists of trays, chemicals(read ALL of the website, they talk about their process), and a lightbulb(no enlarger).
In the end, I've found that LF is a great starting point for ALL photographers, it helps you to look at something, and pre-visualize what you want, and how you need to get there(like with Zone System if you decide to use it)
lots of "stuff" to digest, but the results are worth it!
IIWY, I'd start with 4x5 or 5x7, to get your feet wet with LF. lenses are more plentiful for these formats, and remember that depending on how fast you shoot, you might be going through LOTS of film when first getting started.
just my $.02
if you have any questions, please PM me, if you want to that is
-Dan