I have an EOS that I modified with a SSC, Khatod Smooth 17mm, and a stock Apex. I'm doing this from memory as it has been a while since I've compared the two side by side in the dark…
The EOS has a much smoother beam with a good throw and lots of spill, I find it perfect for biking with (as long as your not going very fast and its on high, I use it on and off road), the Apex on the other hand (in comparison) is mostly throw, the spot gives a great view ahead but not enough spill (in my opinion) and the beams rather bitty (on a wall).
I use the EOS most nights now as the beam for biking is much better than the Apex, The obvious thing would be to place the SSC and new reflector in the Apex to get a generally brighter light.
When I did the EOS mod I noticed a great increase in brightness it's almost twice as bright. I chose the Khatod reflector as it has the most throw and smoothest beam profile, Spotless. I tried a textured Khatod, Khatod Optic 17mm and IMS, I found the textured reflector to be like a wall of light, great for close work, and the optic to be a wide spot, I'd like to try a 20mm optic in the Apex with the SSC, because I think the higher drive current(? – Not sure I haven't opened mine) of the Apex could give a great beam. (Unfortunately I haven't got the bits to try this at the moment)
Dunno about the runtimes but Flashlight reviews have tested them:
http://www.flashlightreviews.com/reviews/princetontec_eos.htm -
http://www.flashlightreviews.com/reviews/pt_apex.htm
Hope this helps
Joe.