I have to admit, I've always liked the look of shower lights too - one apartment I lived in had them out in the hallway as well as in the shower. These were standard 6" Lightolier or Progress cans with the flush white plastic lens. The only issue with these was that they could only take a maximum 60w bulb and the diffuser soaked up quite a bit of light, so they weren't all that bright (although they didn't need to be). That was years ago; nowadays I'd just pop in a 23w CFL bulb which is as bright as a 100w incandescent.

I've never seen or even heard of the ones you linked to - smaller cans that take metal-halide MR16 bulbs (the little bipin reflectors) 20w or 39w. I would think a 39w MH bulb would be quite bright - MH or other HID (high intensity discharge) bulbs are similar to fluorescents as far as efficiency goes.

If you like the look, go for it!

To problems with using shower lights, especially 5" or 6". the light output is terrible.
The regular can is rated for 60 watts, and the IC can ,which is required for insulated ceiling , is rated for only 40 watt.
But in each case the amount of light trapped inside the can is huge ,and the resulting light levels are very, very low.
As suggested , you can use CFL's , but in an enclosed can, with the lights used in a living space, instead of a shower stall, the length of life on the CFL is drastically reduce, because of heat build-up....a very expensive way to lamp your fixture.
There are low voltage MR 16 cans which are rated at 50 watts, which will give you much more light output, but they are a lot more money

The RSA trim/housing you linked to is for an MR16 based fixture at 37 watts max. Using an IRC lamp that could work.

For a 5" line voltage solution I've seen this combination used and it worked well for a contemporary art gallery's office area.

Juno IC20, 212 trim, Philips IRC 45 watt Par 30 short neck 36 degree.

There may be another manufacturer with something similar if you don't like that particular trim.

Here is a link that might be useful: Juno shower trim solution.

Thanks very much for the input - much appreciated.

I think I'm off the shower trim idea - though I do appreciate their sleek look.

Cheers