I've been using Mamiya TLR's for about 30 years--almost as long as I've been using any camera. Even without a Paramender, you can estimate pretty well how to correct. When using a tripod, a center column model works best. It's not perfect but it works pretty good.

My biggest complaint with Mamiya TLR's is that they feel a little top-heavy when used hand-held--kinda "tippy", if you know what I mean. To a new user, they are also kind of hard to understand. They're really not complicated but they seem so with all the levers, dials, buttons, etc. The lack of useable depth of field scales can also be a problem, especially for landscapes.

I've been using a Pentax 645 outfit--original manual focus models--for about a year now. To me, it's a vast improvement in ergonomics. The primary reasons I continue to use the Mamiya is that I like the square format sometimes and the twin lens design is great for shooting infrared films with opaque filters.