I have an Oehler 35P. It took a while to find a good used one. Several came and went very quickly before I was able to jump on them. It took me about 3 months to find mine.
I love it. A buddy of mine and I went to the range today to chronograph some test loads that we are working up. He has an almost new PACT Mark IV XP, that he has only used once before. He won it in a competition match. Today it wouldn't work. It seemed to have a short or something, and he kept getting an error message saying the screens triggered simultaneously. This was without trying any shots yet. He tried unplugging everything, and setting it up again, but the same error message came up. It would alternate between the "ready" readout and the error message every few seconds even when just sitting there. He was pretty frustrated, but we both ended up using my 35P, and he was pretty happy with the results.
It's pretty nice to have the built in printer. We would shoot a string, and press the summary button to get the evaluation of the string. You just rip off the printed info, and stick it in your book (after notating the powder charge on it). It makes for easy record keeping, and minimal work at the range.
The standard distance between the primary screens is 4 ft. Then there is a proofing screen that goes between the two primary screens. You can stretch the two primary screens to 8 ft and beyond I believe by just changing some dip switches inside the unit. I don't have the manual close at hand, so I can't lookup the maximum distance between primary screens. I am just using it with the 4 ft spread, and it seems to work very well, and it's not too bulky. I notice that many chronographs use a 2' spread, and no proof channel.
In any case, if you can find a good used Oehler 35P for a not too unreasonable price, I give it a high recommendation. I don't think there is a better one made for the individual shooter (not commercial) market.