But good condition Tech IV and later are expensive, they are heavy, and they don't handle wide angles well.
I have a thoroughly beaten up Tech III, which has its own trade offs. It's still heavy, lacks front forward tilt, and uses hard to find lensboards unlike later models. But they aren't so expensive when they come up.
EDIT: I suppose I should qualify "heavy" - my Tech III weighs about 6.5 pounds, which is on par with the heavier of very full featured wooden cameras and a couple of pounds more than the light models. It's not a lot in the total kit (especially with my 8.5 lb. tripod I currently use) but it does add up.