Around 5 years ago I got the frenulum cut as it was short and the glans was bent. Now the skin stays back if I place it there and the glans is not so sensitive (autocircumcision). I think it looks better and it it's much easier to avoid ejaculation. As young I had problem with premature ejaculation, but now I can easily avoid.
We have weekly sex, but I only ejaculate a few times per year (I'm 68 years old) if I'm not focused to avoid it. The back side could be a little harder to get erection, but that is not a problem. I would be glad to hear other experiences....
We've been off the karezza wagon, and it's no good. Irritability is up. Seeing each other's beautiful true essence is down.
Incidentally, we had got going last year with karezza and made good progress during a period when I was not cycling, due to breastfeeding. With the return to a monthly fertility cycle, it seems lizardly havoc broke loose. I would say it's all on his side, but I'm sure without realizing it, I'm contributing to the heat.
When I come, my perception of him really changes. I become less content, less generous...
My guess is that if you get too near the edge, and don't calm things down together, this could hold true for karezza as well. I wish researchers were investigating all the options better.
In karezza, the sex doesn't end in orgasm. But that doesn't mean it's anti-climactic.