Wireless flashes - worth buying, and which?

The Olympus R series flashes permit slave through the lens (TTL) metering via a short preflash.

The FL-50R has twice the light output, and much faster recharge (4 AA vs 2 AA), than the FL-36R. It can be purchased used for $230-250.

The FL-36R is much smaller, discontinued, and can be purchased used for $110 to 135. This is what I bought (I'm on a budget).

The FL-600R has the same light output as the FL-36R, faster recharge (4 AA), a small continuous modeling light, and can command other Olympus flashes. It isn't readily available for less than the $300 MSRP.

Another interesting option if you want to try the Olympus optical slave-TTL system are the Metz Mecablitz 58 AF-2, 50 AF-1, and 44 AF-1. All can have firmware updated to respond to Olympus preflash (even if bought for other camera manufacturer systems), and the first two are as powerful as the pro-level FL-50R.

Aside from these, all options I looked at either lacked slave-TTL or important features like both tilt & swivel on the flash head.

Going to manual flash opens up a lot of options. David Hobby of the Strobist endorses the LumoPro LP160 ( http://strobist.blogspot.com/2006/03/lighting-101-start-here.html ), which has a very flexible connections for inexpensive wired remote triggering. I'm considering those should I move to a multiple flash studio setup.