Yeah, I second MM...don't splice both ends.
Treejunkie, call NER, they'll fax you the splicing directions. Have fun with them...measure carefully!
I like the fly. I started using it just a few months ago (I am trying it out as my "short" rope....so I am not really seeing it's TRUE lightweightedness).
12 vs. 16...I'd go with 16. I like round ropes.
Splicing the 12 usually is not possible. Here are two exceptions I can think of. If the hank of rope you have came off a spool that was made much looser than usual (the ropes are often not made the same...2 Blue Streaks can be different, you know) then you might be able to splice the looser woven True Blue. The other exception is Yale's Varilay process where they weave a loose spot in the rope so that they can purposely put a splice there later. That's a good deal.
Ok, I have to go to bed now!
love
nick