I think you need to ask yourself (or your Domme/Dom) how long your lockup time might be. Like has been stated, the plastic ones seem problematic over time in regard to cleanliness, at least for me. None of them have ever cracked on me (cb2000, cb3000, cb6000, the curve). I fit very tightly in all the cb series, so cleaning is difficult, even the cb2000 with open design. Problem with the cb2000 (& other cb's) for me is that I'm all scrunched up inside so skin doesn't ever seem to dry out (sweat, showers, potential pee in the folds of skin). After a few weeks in any cb device, even after trying thorough cleaning with toothbrushes & Qtips & drying with Qtips & a hair dryer, none work 100% & skin starts stinking... rotting I suppose... nasty (think trench foot of the cock. YIKES!). I think it's different for each cock size/shape & how you fit in each device. But buyer/wearer beware. My peehole lined up perfectly in each cb device, however, so I could urinate easily, even at a public urinal without any trouble. The cb6000 seemed the most difficult for me to pull out of & the 3000 had the best fit overall, but neither allows skin to breathe. Definitely frustrating not being able to have any sensation with the enclosed designs though. The cb2000 was the most painful for me, mostly overnight, throbbing while my cock is trying to escape, oozing between the bars... Took awhile to 'get used to', but I do enjoy some pain. *wonders if using a shop-vac to help dry out would work*
Same cleaning issue with a custom metal belt I have... impossible to clean & dry my 'parts' that are covered. Besides, it's more difficult to lead an active life like I do.
I tried 2 stainless urethral devices. Each has a through hole design to allow for urination. Problem here is that my pee flow is greater than what the hole in the device will allow, so pee goes around the inserted tube & sprays all over. Crazy. Besides, just like any catheter, it can potentially/eventually lead to infections so it needs to be taken out & cleaned every 3-4 weeks... at least that's what my doc said when I had a plastic/rubber/synthetic catheter years ago.
I have several stainless metal cages. Still tough to stay dry inside for me. So cramped, but a little better than the others so far. Very durable. Heavier. Look out for metal detectors!
Don't stay outside in the cold too long though...
... & don't overheat the metal if using a hairdryer after showering!
It's all been trial-&-error. Patience. Experimentation.
I've used
http://wholesalebdsm.com/productslist.asp?id=13 to experiment with some fits/designs before buying a higher quality, more expensive product.
Hope this helps. Good luck.
p.s. Pricing there has gone up almost double. I paid $25-30 US for each device.