I suggest the best of both worlds: a folding medium format view camera with a rangefinder. Graflexes will be among the lightest, simplest, and least expensive, and Linhofs and Horsemans among the most full featured. You can use it hand held, or you can use the ground glass. You can precisely position your grad filters because you have TTL viewing (albeit upside down and backwards ). You also get a large reduction in weight and cost over the Pentax, and the ability to use any lens you can fit on a board. Finally, you get some camera movements. You may find the rear shutter of a Speed graphic to help you out if you wish to use barrel lenses.
Personally, I would go for a Horseman VH or VHR (with rangefinder, which works only with Horseman lenses) if I wanted the best compromise of features – including extensive movements – and price. (The VH does not have a rangefinder, so has no hand held shooting ability.) I'd go for a Crown or Century Graphic if movements were not important, and a Speed Graphic if you want a rear shutter for barrel lenses at the expense of a little bit of bulk and weight.
Check out this link: http://www.largeformatphotography.info/roundup2x3.html, and this one: http://www.bnphoto.org/bnphoto/LFN/LFGalleryPress.htm.