Hey there. I am not so sure I am the best source of info on ski technique, as I am a relative newcomer. However, after skiing exclusively alpine last year, I have spent this entire season so far (around 12 days to date) on tele gear. I found a killer deal on some "old school" gear and thought "what the heck, I'll try it".
True tele style is difficult for me. I am still hashing it out. Typically I show up on the hill, do a few runs pulling parallel turns to warm up, then switch over to some traverses in a solid tele stance, beat myself up on some tele turns, then finish the night skiing parallel again.
I follow a website called www.telemarktips.com
which has a VERY active forum with over 3000 registered members. There is a definate hard core group of people that bleed tele, but I am discovering there are more people that use tele gear to get into the b/c, then ski it down, alpine style.
As for changes in technique...I've never taken a class at all, so my technique probably isn't that great, nor is my ability to explain it. However, while using parallel technique I feel my body doing the same on tele gear as it feels on alpine gear. I take a few more tumbles because that heel sometimes "floats" over the edge of the ski, causing the ski to skew when I pressure down on it. However, that cleared up within just a couple of days.
I don't think I'll ever go back to alpine, if for nothing else, the lightweight feeling of gear and the ability to walk around in the boots. No more clunking and falling down stairs. I have no desire to rest my legs on the safety bar of the lift chair, because my gear is so light.
Anyways...I don't think I gave you much positive feedback, all I can say is rent the gear one day and check it out. I think you'll be quite pleased.