Overall, paragraph RP does not work well in SL at all, imho. It goes way to slow. Much of the description text roleplayers expect also is unnecessary because you do have a full three-dimensional set. However, just because you are posting short posts doesn't mean it's a lower level of roleplaying - it's still the same amount of information, just in shorter bursts and using different methods of emoting. Good SL roleplayers learn to adapt and use their environment instead of just reproducing the same format they would in a text RP, and they focus a lot more on conveying their character through dialogue (which is actually what most big fiction editors look for now from new writers). And they learn to do it fast or get left behind.
One term I like to use is ninja writing, which I use in other types of writing, and that's sticking information (about anything - plot, character, background info) without letting people know that's what I'm doing. One writing class I took had us convey as much information as possible through only 200 words of dialogue, and it was really hard, but it is possible, and it can work. You can convey a character's personality through a concise emote or one line of dialogue (the most memorable single lines of dialogue in movies and TV nearly always convey loads about something in the story).
To your point, there are really good groups out there, but it does take time to find them. Not knowing your genre preferences, it's hard to make suggestions, but sometimes you just have to start wandering around and trying things out. The SL showcase in the search panel is a good source, and searching for particular genre keywords is as well.
My solution was to form my own unofficial factions in several RPs, and that made the experience much better. I like to look at most things from a very different angle than most people, so I use that to create a faction that approaches the roleplay from a new direction. I don't really advise making it very leader-directed - people don't want somebody else in charge of them. I leave it very open and let people participate if they choose and how they choose, but I make sure to clarify the deeper meaning of the faction on a regular basis (through ninja writing, if possible).
