Hi raimondo
I did a quick search, even on the CB-X site, but couldn't find a silicone version. Perhaps you can give us a link to a website so we can find the silicone version.
That being said, I am very familiar with the regular CB 6000 S, not the silicone one. I used the CB 6000 S for over a year and would have to say it was a great "beginner" chastity cage. Other than its inherent hygiene issues related to the closed tube design, it was small and comfortable and easy to conceal. I work in an active environment, climbing ladders, and on and off machinery, and had no problem wearing it all day. I was happy with it and got what I paid for.
I eventually upgraded and switched to a custom made Jail Bird from Mature Metal. The old CB was a great "starter" cage, but the hygiene problems and constant daily maintenance made it difficult to wear full time 24/7/365. The new one from Mature Metal is an open steel cage design which is easy to clean without ever removing it and can be worn permanently.
There is nothing wrong with the CB series, you get your money's worth for what you pay for. I assume you feel the same way about the Bon4. I think the are both economical "starters" or "beginners" cages, but if you and you keyholder want to keep exploring the chastity lifestyle, perhaps you might consider looking into investing a little more money and look at a stainless steel design. You might save some money over the long run. I have a CB 6000 sitting in a drawer, and a CB 6000 S sitting on a shelf like a trophy after we bought the one from Mature Metal. I've had it on for about a year and a half and it's probably the last one we will ever have to buy.
There is a website called chastitymansion.com, and it has some great forums for all makes and models on the market.
Best of luck !
You know what they say, be careful what you wish for !
brian