Thanks for the sugestion! Nowadays I use a Pentax 67, and I'm really researching a lot to know if it really pays to buy an LF..
Yes and no.
6x7 is a very good negative size, however there are other considerations.
Ilford FP4+ 4x5" film, is 125mm x 100mm actual.
The image size on my negatives from the industry standard film holders is, 120mm x 95mm actual.
That is 11,400 square millimetres of image, compare this to what your actual image area is on your Pentax 6x7.
In another life working in a professional lab complex, we had every format from 35mm right up to 10x8" film coming through for enlarging or drum scanning, mid 1980's. Most of us agreed that good all round working imagery started from 6x7 negatives upwards, that is they could go to magazine or poster reproduction with reasonable quality. Best quality started at 4x5" and marginally improved when using 8x10". The best bang for the buck, image wise, was 4x5". Best bang for money, was 6x7 and if taken with care, often looked pretty good compared to 4x5".
For field use, a folding view camera, like the Toyo you mentioned, would be excellent and with the metal body quite robust. I personally know someone with one of those and it really is a nice camera. The revolving back is brilliant, something mostly only seen on a monorail.
For real architectural stuff, a monorail of some kind is hard to better. There are some excellent technical small and lightweight monorail cameras around, but they sort of go up in price and within reason, unless you live in the USA, they are sort of hard to come by.
I have a Toyo 45G which is a very good monorail, but it is not light and not that small. Geared movements make it a breeze to use.
I also have a Shen Hao HZX45-IIA, one of the older Shen Hao models these days, but a reasonably good all round camera. It has generous front rise and fall, rear rise and really handy rear shift. I also have a bag bellows for this, which is interchangeable in about 1 minute and really easy to carry. I use bag bellows when doing architectural stuff and lenses 150mm or smaller.
http://www.shen-hao.com/PRODUCTSabout.aspx?i=950&id=n3
If you really like to think about what you are taking, then sheet film cameras are really great. The size of the exposed image that you get to work with, really does make a difference. The ability to move the lens in one direction and the film in another direction, really opens up a whole new world of possibilities.
View Camera Technique, by Leslie Stroebel is perhaps the best all round technical book that will give you insight into what is possible and what is available. I have the 7th edition, which has 376 pages of information. I would suggest you may wish to find one of these books, most, if not all of your technical questions will be answered; it cannot answer the question of your desires though.
Mick.