I think it is a necessity that will save your helis more than once in their lives...

But like was said, its personal choice and goals really.

If you are learning though, i found nose in to be easier higher up (where you can see alot of the bottom of the heli, but still be far enough out away to be safe)

Not only was orientation easier for me at a higher altitude, but it give you more time to get the tail back around and get control of it when you do get out of shape a little bit.

If you have one (and you should, i think, but again, just preference), use a sim. Realflight has an awesome heli-hover trainer now. It gives you a circle to stay in when hovering, and if you leave that circle, you explode. You can set it to start you at random orientations so that its not always tail in...Im flying in forward flight doing basic stuff (figure eights, stall turns, ugly funnels) and i use the sim for learning new stuff, but i still use the hover trainer. For the sheer fact that you can set it to start you inverted (even randome between inverted and normal) so that its a surprise, set the circle to small (5 feet) and it becomes a challenge and a great learning tool for me, in inverted hover...

Saying that just made me think of something else as well. If you cant wrap your head around nose or side-in hover, you wont have a chance with inverted hovering. BUT -- learning nose in was the hardest, once you train your brain to think differently, the other orientations come natural...so its worth the effort.

Have fun!