I have used loop thru connections to my 3200 with varying success. I can't remember the initial experiments, but I think I tried with my Fortec Ultra, and it worked on some S2 transponders, and didn't work on other transponders. I think I also tried my Coolsat 8100, also with varying results, however the negative results COULD have been caused by the hot swap reboot issue I mention below.
Now, however, on C-band, instead of using the passthru, I'm instead using a splitter. Ie I have a splitter that passes power to my analog receiver, and sends one coax to my Coolsat, and one to my 3200. This seems to work fine on most transponders. There is signal loss associated with the splitter, however although the passthru connections generally have amplification, they also seem to introduce noise. Ie using the passthru isn't a signal problem, but rather a noise problem, and the Ultra and Coolsat seem to be noisy.
On Ku, however, rather than doing the splitter thing, I AM using the passthru of my Diamond 9000, and it seems to be fairly good quality on qpsk transponders at least. On DVB-S2, I've mainly been trying to get the LaPTV channel on AMC21, and haven't had a lot of success, however I haven't had much success with this transponder direct to my STBs either. There aren't that many DVB-S2 feeds on Ku, so I haven't really had much chance to experiment with sats that I'm not viewing through tree limbs.
So basically I can't remember if I've ever found a Ku S2 transponder with the 3200 through the passthru, but on C-band, I had better results splitting the signal than going through the passthru.
One thing about the 3200, however. I've found that 90% of the time I've done a hot coax switch, the 3200 will still work fine on DVB-S transponders, but it won't work on DVB-S2 transponders. To get S2 to work again, I have to reboot the computer. I still do the hot switch, however, because sometimes I AM able to get it to work and it saves the time wasted by rebooting. So if you ever have trouble locking an S2 channel, but are lockind DVB-S channels fine, try rebooting.