What you see on the RFC's site are only reference links to current proposals. What is going to be in the actual RFC might not encompass all or some of the variants you mentioned.

QRP and Ultrapeers go hand-in-hand. Ultrapeers will be mentioned in the RFC (currently as an "optional" implementation), per the LimeWire specs. On the GDF, there's some discussion about using SHA1 with Ultrapeers as well, but we'll have to await the outcome of that one, as not everyone was very accepting to that idea. Nonetheless, HUGE will also be included with the RFC, probably as an optional item.

The drawback of some proposals is that they don't re-use the code of another proposal or implemented feature. For example, QRP uses different hashing (albeit for obvious reasons, as they're not used in the same way) than HUGE. That would require two different hashing methods within the code. It bloats the Gnutella client unnecesary.

It's probably good to quitely follow the GDF's progress (see http://groups.yahoo.com/group/the_gdf). Occasionaly, there's some mud fights, but usually developers can come to an agreement or offer very good ideas. Actual participation does require you to be prepared for a mud fight tho