I doubt if it's possible to generalise about the bokeh on lenses of this era. Triplets generally tend to have a certain "look" in the corners where the sharpness breaks down, though. Bokeh is so subjective, and so dependent on fine details, that I'd expect it to vary quite a bit from sample to sample.
As Ian says, the Nettar was the bottom of the line, and I wouldn't expect much of it. The one Trinar I have (on a prewar Wirgin 6x9) is excellent; sharp in the centre, reasonable (by triplet standards) in the corners, not much vignetting and a lot of character. If you have to make a call just on the lens names, I'd go with the Trinar.
It's going to be a little challenging to use any scale-focussing camera for street photography, but I expect you know that...
-NT