I use a 4x5 Field all the time. Mostly for color now nut I still do some B&W... I also have an Arca 8x10 F-metric and a custom Canham 11x14 back for the 8x10 (simply detach the bellow and 8x10 back, and replace it with the 11x14 back and bellows). The bigger cameras are strictly B&W (for now).
IMHO Arcas are the best engineered and easiest to use. I started with an Omega (Toyo) monorail back in 1982, eventually replacing it with an Ebony in 2001. I used the Ebony twice. Didn't like it... it's like a Rubic's Cube. Switched completely to Arca in 2006.
Others will disagree, but that's my experience.
If you want an Arca... call Rod Klukas at Photomark in Phoenix, AZ at (602) 244-1133 - (800) 777-6627 or visit this web page to get his email. http://photomark.com/large_format.html
Tell him Rich Coda sent you.