Ian,
The Turbo gives you the ability to attempt a glide that a prudent un-powered
sailplane pilot wouldn't try, therefore I would place you in the same motored
category and *use of engine* penalty would apply.

I do agree with your post that suggested;

Standard class-------------No Engine
15 Meter----------------------Turbo only
18 Meter----------------------Engine
Open---------------------------Engine
Sports-------------------------??? I don't know, what do the rest think?

If this rule became *stable* (Good luck on that) most pilots in each class
could be appropriately equipped and inequity would, for the most part, be
eliminated.
JJ Sinclair