What do you mean with "panel", do you mean the lens board release catch, or the back (sliding back usually) holder?
As far as I know there are three versions of the back release and two versions of the lens board release, but I don't know for sure.
I (think I) have a 2010 model, which has the second back release and the first front release. My back release is a wheel plus a safety button, two-hand grip required to detach it, I like the mechanism and it feels safe. I've heard that the first revision had a less safe fastening, and I think the current clip-lock is a bit smoother to work with, but I'm not sure.
On the front my lens boards is attached with a simple lever, no pressure on the board which requires very high precision of the board thickness to not cause micro-tilt precision errors. I've measured this and in the worst case it could lead to a less than 0.03 degree tilt error. I don't think that should cause a problem in normal photography, but the newer clip-lock is still better in that regard.
Below an image of the latest revision (2012?) of the Techno:
I did not find a rear view of that, but I think the back release looks about the same as the lens board release.
Here's my variant (2010 I think), note the wheel plus button to attach the back:
This is an image of the first variant (2008) (no safety button on back lock; no partial extension of rail):
I've heard some bad things about the 2008 back release and other possible issues, so I'd be a bit careful when buying that, perhaps ask Linhof Studio or Linhof directly if there could be problems and if it's possible to upgrade the problematic parts.
I have myself only used my own Techno so I haven't in person seen the others.