Referring to "TR 0 -4," all but "OT TR 0" are done with eyes open.
When I first did the "Comm Course," there was no eyes-closed TR-0, there was only TR-0, and it was done for two hours straight, and then it was on to "Bull baiting" and then to "TR-1," etc. My first TR-0 twin was a guy who - at lunch break - followed me out of the Org and to a restaurant, where he sat with me and told me how, in the future, when we're all "OT 8s" (then the top and final OT level), the rest - who remained non-Scientologists - would have to be isolated on an island away from the rest of us. This didn't seem like a good idea to me, and I was glad when he wasn't on the course when I continued with it that afternoon. It took two days, left me fairly impervious to normally unpleasant stimuli (except from Scientology), which was a fairly enjoyable feeling, a tendency not to blink, and to calmly acknowledge people.
I found it to be a positive experience, although, looking back, can see how it "set me up" for deeper involvement.
The most notable Comm Course story, of which I know, is a fellow who did the just released "Hard TRs Course," that this person regarded as an inexpensive means of therapy for his wife (it cost, I think, 35 dollars) and a kind of odd head-trip for himself.
It took about a month, and I think his wife benefited - was more emotionally stable - and he seemed to get a kick out of it too.
This person had the wisdom to recognize that this was probably as good as Scientology was going to get - especially judging by money-spent/potential benefit ratio - and firmly rejected any future involvement with Scientology afterwards.
He ensured this future non-involvement in a novel manner, when he wrote his "Success Story" at the end of the course, describing how (to paraphrase) "Now that I've completed the Communications Course, I'm going to become a leader in the Hare Krishna movement."
The joke wasn't appreciated, and that ended his and his wife's involvement with Scientology.
For what it's worth, here's a thread on TRs:
http://www.forum.exscn.net/showthread.php?t=944