I have only used the Tachihara. I think the camera will last a lifetime, treated well. Unfortunately, our students often have trouble with the concept of "treated well"! Be careful of the toggles that hold down the rear and front standards -- our students managed to break them off (got replacements thru B&H, but this was several years ago.)
A camera that has faired better with student use (abuse) has been our two Horseman Woodman 4x5's. As light (if not lighter) and more simply built than the Tachihara, but still with all the movements needed for a field camera.
What is the condition and the movements of your old camera? If it is working and has the movements you want, I would also suggest thatyou thinking about getting a slightly longer lens...150-180-210...that would offer a wider image circle for taking advantage of the movements for the camera you have (if it has them).
But I can understand the desire to buy a clean, smooth running tool.