I have a Kyser capo which has quite a grip--when I used it on the fifth fret of my Strat it pulled the strings so much that they were stretched out of shape and had to be changed. is there a good fix for this or would an adjustable capo work better?
Your Kyser might be fine if you put it very close to the fret on which you are using it, rather than further back into the space between the frets. - This applies to all capos.

I've used all sorts of capos, including the Kyser, and my favourite for simplicity, tuning stability and light weight is the Planet Waves NS and similar screw capos. The only thing I have against it is the colour, small things like that should be high viz.
(Apologies for bumping capo threads again...)
You run the risk of stretching strings with any non-adjustable capo. I work for G7th capos, and our best capo is the Performance 2 (http://www.g7th.com/performance-2-capos.aspx) because you simply squeeze it to attach to the guitar, so you set the tension with as much pressure as you would use for a barre chord and then you know you won't pull the guitar out of tune.

To be fair, Kyser also have a specific electric guitar version that applies less tension than their standard model. G7th also have a similar style capo, the Nashville (http://www.g7th.com/nashville-capos.aspx) which is able to apply a similar amount of tension (although we've set it to be less than a Kyser) but it's easier on your hand because we moved the pivot point on the capo :-)