I have a 4x5" Tech V and recently acquired a 6x9 Tech V. I'm used to shooting 8x10" and occasionally 11x14", so the 4x5" is my compact handholdable camera, and the 6x9 seems all the more so.
There's a good overview of the Technikas at cameraquest.com.
You can have new lenses cammed for a Technika by Marflex in the US and Linhof in Europe, but not for all older models. If you're looking at a Tech 70, call Marflex to be sure they'll do it. I'll be sending my 6x9 Tech down to them to have three lenses cammed probably in the next week or so. If you have an old 4x5" Tech III, Richard Ritter will grind cams for them.
If you purchase a used Tech, though, try to find one with some cammed lenses, and if it's a 6x9 Tech or Tech70, with a set of three cammed lenses, because it's expensive to have it done after the fact.
The 4x5" Tech V is the most versatile camera I have, so I like to travel with it. I can use it on a tripod with movements like a view camera for landscapes, architecture, and still lifes, or use it handheld with the rangefinder and Grafmatic 6-shot filmholders like a press camera. The rangefinder is also handy to confirm focus in low light and for portraits, because you can check focus with the rangefinder while you've got a filmholder in the back.