Dont Change The Horse In Midstream!
Dan, me old son.
You are going to have to be firm with those folks.
Say right out loud, I would like to stick with one kind of glider.
So do your training in the 13 or in glass, but changing about is not a good idea at all. Okay, the instructor in the back seat gets changed about, some are getting on a bit and fixed in their ways (like me!). But you have to tell him (almost never her, alas)what you prefer.
I didn't start gliding until I was 50, (last week, I tell my students), and it took 65 airtows to achieve solo. And to learn the landings I had to cheat, and do a bit of that in a power plane. Consider a motor glider if they have one up there, BUT
Very likely you are not ready for landings yet. Get confident in handling in the upper air, practice, practice. Show that you can maintain an approach attitude and speed. Do a coordinated turn, maintaining speed.
Use airbrakes, maintaining attitude. etc. etc etc.
Then ask the instructor to demonstrate "landings at altitude"
This works for my students. In a K13, at altitude, we set approach speed, we set half brakes, we pretend we are near the ground, and slowly ease back, ease back, ease back, and having "landed" recover from that and do it again. And again.
Then the instructor demonstrates the landing. Nailing the approach speed is vital, if you cant maintain an approach speed at altitude,work on that first. After watching the instructor do a landing, you just go up together again right away and do it again, only this time it is YOU!
I feel that instructors try too hard to provide "value" for students, and do not do sufficient demonstrations.
I also nearly chickened out altogether, the first time my instructor demonstrated unusual attitudes, but came back. Again. And again. If I could do it, you can too. Go for it!
Mary