I have the Canon 100mm non-L macro, and it's great. As true macro work (1:1 or near) needs to be done on a tripod, the Hybrid IS is not that useful for macro (particularly as it's not just lens shake that needs to be accommodated for..., but certainly it CAN help in a few closeup, but not macro settings.
Furthermore, I occasionally use the 100mm non-L as a 'quick portrait' lens, and the AF 'focus range search' limiter does help here. I don't know why people complain that the nonL's AF is slow (it isn't on mine... esp on my 7D, that USM focus is really quite speedy, snappy and accurate!). I have used the Canon 100mm L macro, and it's a bit better, but really splitting hairs. If that much weather sealing is required, sure... get it!
About Canon zooms (70-300mm L vs 70-200mm f/4 L) - I would get the 70-300mm L any day. At the same focal lengths, the 70-300mm's effective aperture is ALMOST the same anyway... plus it gives you an extra 100mm. I use my 70-300mm for outside (mainly wildlife, birds, some other aspects.. .very occasionally informal sports). The IS of the 70-300mm is a tad superior to the 70-200 f/4, and the USM is basically the same.
If you are going in low light, sure the 70-200mm f/2.8 IS (esp vII) is particularly useful / good.... but for me, when I am in 'low light' - I actually want REAL fast glass, and that means primes (eg f/1.4 - f/2).
Cheers. All the best with your decision / outcome.