I purchased a Progasm Jr. a couple of weeks ago. I based that purchase off of comments on the forum and reviews of the products. After three sessions of nothing, I was disappointed but undaunted. It seemed as though the Jr. was providing very limited stimulation to my prostate. I had tried the passive relaxed method along with multiple positions and contractions, but hardly felt any sensations. I decided that because I am 6' 2" that perhaps I needed more length and girth (I'm slim, but the Jr. was so easy to insert and didn't seem to result in any particularly full feeling).
So I ordered the larger Progasm and was rewarded with much improved results. After a shower, I had no trouble inserting the Progasm. It provided a much fuller feeling and the urge to urinate that I had not experienced with the Jr.
I used the relaxed right side approach and after a period of breathing I moved to some contractions. It took awhile but after 30-45 minutes I was rewarded with some very pleasant sensations that intensified with additional relaxation and contraction cycles.
I did not experience an orgasm, but I had an excellent session with the promise of an orgasm on the horizon. And in any case, the sensations were some of the best I've felt in who knows how long.
I think I disagree with the concept that the Progasm is for experienced users. With the right lubrication it was easy for this beginner to insert and provided better feedback than the Jr.
I'd advise beginners not to shy away from the larger Progasm from fear of its size. Size may be just what the beginner needs. I'll probably give the Jr. another try after I have really mastered the Progasm. But for right now I am going to be concentrating as much of my time as possible on the Progasm.