Do you have the option of diving doubles and/or access to EAN50 or EAN100 for deco?
As Kev mentions the Odyssey has doubles and will blend up whatever back gas and deco gas you like. I tended to use 60% for most of my deco dives in Truk, due to the benefit of hopping on your deco gas sooner/deeper. Cost of 02 wasn't terribly high, but if you run V-Planner for a typical dive you'll see that total dive time and deco time is essentially the same with 60% or 100%, so why pay for the extra CF if they don't do you any good. Just a matter of how shallow you are when you make your switch. (Actually, with a 20min bottom time on 24% back gas the dive is 1min shorter on 60% than if on 100%.)
Also need to look at required gas volumes to ensure you can carry enough of the leaner 50-60% mix (between bottom time and reserves you could get caught short) which would be the only reason I'd go with 100%. Though, if you ran short on 60% and had to deco on back gas or the reg hanging off the boat it wouldn't be terrible.