What springs are you talking about ? aren't we talking about the regular emulsion 2.0 Fox shocks ?
Also Fox 2.0 have aluminum bodies, (they have a version that is SS and can rust fast) i understand that Fox uses zinc plating for the shock bodies, even in the SS versions, i think the 2.5 CO's have steel bodies, and prob one of the reasons some people find this option to a little more problematic if they live in the salt belt, but again, i'm not familiar with Fox in general and anything else they do besides the factory performance 2.0 shocks, i know pretty much almost all manufacturers do sell something to protect their stuff from the elements/harsh driving conditions, and you can also use home made stuff, so if your invesment is rusting out, there are things you can do to help prevent that.
I know their rods (2.0's) are made of stainless steel with a hard chrome plating, if they rust is because the shaft was pitted and the previous owner might have not cared too much for his/her equipment since you mentioned buying the truck used, pitted/rusted shafts are a sure way to damage your shock internals/a way for those shocks to stop working as they should fairly quick, and just like people using fluid flim to protect their vehicle underbody and parts from the elements, you want to protect your investement as well, you throw away your $80 shocks when they're done, with race shocks, you might pay $80 to get them rebuild (seals/oil etc assuming you took care of yout stuff), but you have to take care of them if you don't want them to look like crap if you have to drive in the winter with them, just like everything else that can rust because salty conditions.
As for the reservoir, yes i agree it helps with some cooling, their main task is to separate the nitrogen pressure from the oil using a remote location for the Nitrogen, so the shock cylinder is filled 100% with oil as the piston cycles up/down while the nitrogen remains in the reservoir, that's it, it allows for a longer shaft if needed as well, without the res, the IFP is placed within the body of the shock itself, so the shock is filled with less oil, cooling in their case is an added effect but not the main purpose, no difference in feeling one way or the other if you're not cycling the shocks fast enough to need the extra oil, the reservoir helps resist fade and cavitation, again nothing here if you're driving to the mall back and forth, though you can say the res can help the shock last longer just because how much oil you can feel in, think about it as an HD hard cover or trans pan, more oil, longer service, less heat, though in the res case, the res could make the valving more consistant if you wish because you have more oil/gas to help you with, so the performance benefit will be there.
Cost of rebuilding either version is pretty much the same, in any case it's not a waste to have them, extra cost if you need them sure, i wish i could have added CDC to my future shocks for example which is another feature, again a feature i may need but choose not to have because of the extra price
, maybe later on though who knows, you can always send your stuff in to get extra features added, go with a different valving, and add a bunch of other options, or even do them yourself, i DD my truck, i wanted the res, and i know they'll come handy on the weekends as my truck sees the dirt/desert, only thing special about living in the Socialist republic of Commifornia....
