I've played with High Fidelity. It constantly disconnects, and it can take over a minute for an area to load enough to provide basics like 'a floor to walk on' or 'the shapes of buildings'. Second Life ran a hell of a lot better on my crappy old computer on a crappy Internet connection; the graphical improvements of High Fidelity are scarcely better and certainly don't justify the poor performance.

Oh, and it's already full of furries, so you might as well torch it and start again.