I think stretching is awesome LOL! It hasn't hurt for me yet. I had my 16Gs in for about a month, then when I was at Hot Topic I asked the guy if it would go in easily and he said yeah. He was pretty much right too. I had no troubles putting them in at all.
And yes, I won't go too large, too large seems like too much to handle IMO. On some people it does look good though, just I only want to get smaller gauges and nothing big at all.