I have been using Canon HF and HF-S series cameras with Lanc for over six months and have had lot of problems with them getting out of sync and staying out of sync even after power cycling.
Some combination's of cameras seem to be all over the place as far as frame sync when power cycling. Random even.
A friend of mine and I kludged together a two camera LANC controller and tried to come up with a way to compensate for this but the seeming randomness of the sync start has made it difficult.
I'm beginning to think that it is an inherent problem with Canons.

Should I try Sony?

Let me clarify.
When starting the cameras they often start out of sync by as much as 16.7 milliseconds. I can power cycle them numerous times and never get them closer then 12 ms.

This is why you want to use cameras that have a genlock input, along with a sync generator. The cameras will lock to the sync pulse made by the generator, and you'll never worry about this again.

So far as I know, the cheapest cameras with genlock are the Cannon XF305 for $7500 or the Sony EX3 for $8300 (with a lens). Black Magic and AJA make low cost sync generators for $300 & $400 each.

Thanks but I am aware of that.
I need an inexpensive "small" camcorder like my Canon HF-21 and
it has to have a LANC interface.

My pair of Sony HDR-HC7s reliably power up with sync less than 1ms apart when using the LANC power-up pulse (pull the LANC line low for >150ms.) Drift is minimal; stays pretty much in sync for 15-20 min. before I need to do another power cycle. Certainly not as good as a real genlock, but not bad for an inexpensive HDV camcorder.

Sony HDR-HC7 Camcorder Review - HDV - CamcorderInfo.com (http://www.camcorderinfo.com/content/Sony-HDR-HC7-Camcorder-Review.htm)

Thanks very much, that's just the kind of information I was looking for.
I'll check it out.