You can certainly give it a shot, easy enough, that's the beauty of external enclosures - I had a Belkin enclosure, and plenty of drives had their day in it. Depending on which PC I used (at the time, one had an ATi SB400 chipset, the other Intel ICH8R), I could either get 8x or 12x out of it.
Like Drage said though, I wouldn't burn at 16x or over anyway for a good burn ...I tended to use 8x on both setups.
EDIT: On the PC I use these days, there's a card reader, external HDD, mouse and keyboard all using the USB. I used to disable the card reader/additional HDD, but these days I don't bother and 8x burns are fine. Depends on resources of the PC though.