I really like the idea of a MF view camera but also understand the limitations of lenses. Do you feel the Horseman is well enough for architecture? Generous front rise? Obviously if you used a lens for 4x5 on it then you would have plenty of image circle, but is there enough offered by the camera? Do you have an photos in your gallery taken with the VH-R?
The movements on the Horseman VH-R work best with slightly longer lenses, e.g. 90mm and above, due to the clamshell design of the camera. Monorail cameras with dedicated wide-angle bellows are more suitable for wide-angle lenses when you need lots of rise, assuming the lens has adequate coverage. Given that you're experienced with LF camera operations, your choice of camera will depend partly on what types of lenses you're most likely to use. I used lenses ranging from 65mm to 210mm on my Horseman, and had a dedicated RF cam for my 150mm. All had sufficiently large image circles to make full use of movements available.
The series of photographs from Pleasant Hill, Kentucky (e.g. Ceiling Light and Drawers, Dormer Abstraction, etc.) were taken with the VH-R handheld, due to their restriction on tripod use indoors. I was able to brace the camera against various surfaces to keep the images sharp. Also a number of photographs from along Eagle Creek. Sharpness has never been an issue with the camera/lenses, although I'm not an ultimate sharpness junkie.
I went through the dilemna of whether to move to a 6x7/6x9 view/field camera back in the mid 1980's. I was shooting 645 and happy with the quality but frustrated by the lack of movements for certain images. I had been using 5x4 for about 10 years but my monorail cmaers was too heavy and impractical outside a studio.
In the end after weighing up the various possibilities I went for a 5x4 field camera knowing I had the option to use a 6x9/6x7 back. I don't have a preference for format and happily work with 6x6, 6x9, 6x17 as well as 5x4/10x8.
I would expect most Fuji lenses such as your 135 to be really pretty good (although it may depend on its age). The weakness here is more likely to be imprecision in the camera - lack of accuracy in ground glass/film registration; slight movement in the camera as you tighten up lock knobs; slightly out-of parallel standards; inaccuracy of focusing on ground glass (which is more difficult on MF) etc. MF is much less tolerant of these issues than LF. That's all.
Re: Horseman VH-R - check how wide you can go with a design like this, as it might not be able to properly use the wide angle lenses you need for architecture - there may be restrictions from both the body and the bellows. I don't think Horesman make their own lenses - they may be rebadged Fujis anyway (nothing wrong with that, though).
Right, ic. To name names, Tokyo Optical, who make Topcon and Horseman lenses, own Horseman. Good lenses, too.
Have you considered a Fuji GX680? They seem to be remarkably cheap and functional, though not the most portable.
At this point I'm really leaning toward the Shen Hao 6x9 from Badger Graphics. Seems like a great little camera with tons of movements, lightweight, and not too bulky. The GG also flips out of the way when the back is attached. So there is no need to remove the GG for every shot. Now I just gotta sell my Hasselblad 500cm body I have sitting around to help fund this.. :)