I am planning on three, which is currently what VRChat supports (2 feet, hip). I've seen it and it does really well with 3.
I really wish that these VR Worlds had content creators that were at the level of some of the ones in SL.
I don't want anime or cartoon avatars. I'd like something semi-realistic.
I just went and checked NeosVR on Steam. From them:
Fully configurable full body IK with up to 11 tracking points (head, hands, hips, feet, chest, elbows and knees)
So, Head, Hands (Controllers) count as 3. Add Hip (1) and Feet (2), that will put it at 6. That is what I am planning on.
So, I retract my statement about 11 trackers being 1100. I didn't realize that they were including HMD + Controllers.
Neos would be HMD, Controllers, + 8 Vive trackers. 5 more points of tracking over what I am planning. From what I've seen they've added chest (1) + knees (2) + elbows (2).
Here is an example in VR Chat with 3 Vive trackers (6 total):
I just stumbled across this in /r/virtualreality
It is the same avatar as the one you posted. It has her dancing. It appears that she is only wearing trackers on feet and hip.
She does not have one across her chest, or knees, or elbows. I would argue that 6 points of tracking does a sufficient job. I'm jealous of the wireless headset. Although, I think I want the resolution of the HP Reverb G2 over the Wireless adapter and a Vive. I really don't want to dance I don't think. I'd bust my ass. I do want Full Body Tracking though. That's a lie. I do want to dance, which is absolutely crazy. I'm going to put blackout curtains on the windows and lock the fucking doors, but I do want to dance. I think that's fucking incredible. As long as the doors are locked and the windows have blackout curtains over them and no one ever knows. I may have to kill the dog as she'll be the only witness. I'll miss her, she's a good dog. In all seriousness, when I buy trackers, I may buy a 4th so I can put it on her collar so I can see when she comes in to see what the hell is going on.