As far as performance goes, I would say the 1000 has it there due to deeper fire box allowing a bit more distance from the flames to the grates along with the extra flavorizer bars to distribute the heat better. You can always take the extra 8 bars out if want more clearance for something like a rotisserie as well. But, I dont think it is all that big of difference between that and the Silver B. It might come down more to the thermoset tables on the Silver series vs the wood/durawood on the 1000's.
Either style would serve you very well and if rehabbed well, will probably last you longer than a brand new one.