When I am live baiting I am tying a five turn uni knot to my live bait hook and looping the other end and crimping at the swivel end of the trace.  I'm using 80lb fluro and thinking of going up to 120/150lb fluro shoud I keep using a uni knot or should I crimp at the hook end as well, don't want to hook and lose a big fish because the knot has slipped.  What do you guys think???

I tie for anything under 150lb usually and crimp from then on up on both ends of the trace of course.

Comes down to how comfortable you are with your knots on the heavier gauge line. If not comfortable then by all means crimp it but just like with your knots, make sure ya do it right.

Found a good article on the site on crimping some time back. Worth the read
http://www.fishing.net.nz/index.cfm/pageid/56/view/yes/editorialID/295

fluorocarbon's harder/denser than standard mono nylon and a bit trickier to tie 100lb upwards which is the main reason I crimp it (personal preference though).  I start crimping f'c at 100lb using tiny anodized copper crimps (much better than the alluminium jobbies), end result turns out more discrete and reliable than any knot.  But with standard nylon leader will tie anything upto 200lb.

thanks for that link jk. i guess it does not matter if you crimp or use knots, just do it right the first time when the line comes tight it'll be all good