With the WP-DC34 you can't use the rear dial directly, but the functionality of it is easy to learn using an alternate button arrangement. Practice a little while on land, and it's easy to get used to it. Also, you can save two set of custom settings (C1 and C2) and that way can have the general setup you want always handy. I set mine up with C1 for macro with strobe, C2 for near focus (2') with strobe, and then set my manual settings for general shooting without strobe. Easy enough to do and then I'm not doing much but switching between three presets. I believe the front dial functions on the G12 can also be worked through an alternate button method as well.
I have a G11, WP-DC34, and Sea&Sea YS-01 strobe using an optical trigger cable. Works great, including TTL modes with the strobe. I blacked out my housing to effectively block all light from the internal strobe except where the optical cable pickup is located. I highly recommend the S&S YS-01, for the money it's a great little strobe. Not too big, recycles quick, uses standard AA batteries (I carry two sets of NiMH rechargeables), and has a LED focusing light built in. And the TTL mode works great with the G series of cameras. You can pick up this strobe for around $400, an optical trigger cable for about $30, nice arm for $150, and WP-DC34 housing for $180. A pretty low cost way to get into underwater photography.
