well since you already have a CF-based camera, i suppose you want to stay with CF? the v1 is a decent camera, except it uses MS.
i have a s50, roommate has a v1.
both are good cameras, the v1 will probably be a little harder to carry in your pocket vs the s50 becuase of its particular dimensions. ergonomics on the v1 could be better, its a little awkard to hold and operate it. lcd is smaller, manual controls are slightly harder to change. i do like its focus abilities though - and it is a very quiet camera compared to my s50.
s50 has excellent battery life, cant say anything for the v1. they both use identical 5mp sensors, only difference in the output images are results from different lenses and post-processing.
canon has raw output, which is a plus for me.
shutter button could be better on the v1, but the set button on the s50 is pretty bad.
v1 has 640x480 movies, s50 320x240. review is better on the s50, v1 has live histogram though.
s50 has more versitile focus options, TommyVercetti says otherwise, but the s45/50 has "infinite focus" positions which you can manually select ala the g3/g5 - also the s50 has 9 focus points in auto mode, the v1 only has 3 i believe.