My personal opinion is that you would be happier with a conventional lens from 250mm to 300mm unless you have a severely restricted bellows.

I use a 250 Fuji CW-M and find the focal length complements the 150 nicely without a large gap. However, using the 250 requires efficient use of movements and stopping down (assuming landscapes). It is interesting to note that DOF tables show the 250 as having the same DOF at F32 as the 210mm at F22. So, you are going to use movements and movements with a tele lens are different. Tilt, for example, must be calculated from a point in front of the lens instead of at the lens middle section. Similar to the leverage theory, a little tilt will move the best image quality off the film (it's easier to draw a diagram and see the result than for my limited technical mind to describe). Naturally, you can see this on the ground glass.

You might look hard at the Fuji 250 or the Nikkor 300M F9 before you buy the Tele-Artar. IMHO, they would be better options. Don't let the F9 on the Nikkor throw you off - it is extremely easy to focus and offers a bright image when a fresnel is installed.

I'm also using a Nikkor 300 right now. The Fuji is larger and more expensive new (Fuji's are harder to find used and the CM-W version is very new). Image sharpness is exactly the same. With my bellows of 325mm, the 250 focuses much closer.

Mike