I can see why Cyclers might appeal - a larger spacecraft to act as home for a cruise from one planet to another....BUT...I've never seen a couple of issues that immediately caught my attention addressed...

You have to get onboard this thing, and it's not going to wait at a bus-stop for you. A typical Mars trajectory has a two week launch window (consider the MER's for instance - Opportunity ended up needing most of it's window before launching ) - but if you have to intercept a spacecraft on a fast flyby - then that window is going to shrink, a lot, to perhaps only one or two launch opportunities in a space of a few days - and infact without packing a huge ammount of delta-V - I can't see how you could have anything other than a single instantaneous launch window. I dont know the stats on getting LV's to the pad and succesfully launching months at the first time of asking without fail - but I doubt it's more than 50%

Secondly, what do you have to launch in that window...well, the crew, all their supplies for at least a round-trip to mars and back ( 3, 4 years worth? ) any and all potential spares for the cycler, and one presumes you want to land when you get to Mars, so a spacecraft for landing at the other end with all it's life support systems- and assuming Mars-Semi-Direct architecture, you'd then launch with an pseudo Earth-Return-Vehicle to catch up with the return-cycler and have all the same problems again, in reverse.

Given that you have to launch the crew, their supplies, consumables, landing spacecraft with all of it's life support systems, manouvering fuel, etc etc - what is it that the cycler provides that you wont already have to be taking with you apart from a slightly bigger living space which could probably be provided by one of the proposed inflateable habitat designs. Granted, you could use a SHLV to launch a cycler that provides increased radiation protection, but I dont see any other benefits.

Maybe I'm missing something - but I dont see THAT many advantages to a cycler, and it would impose a lot of constraints to the rest of the mission architecture.

Doug