Not exactly, the warranty is the same unless you plan to drive over 125,000 miles before 8 years is up (it doesn't sound like the OP plans to put a lot of miles on the car). Than means that buying a newer S60 for low mileage driving would actually get you longer warranty than an older S85. As for faster charging, that only applies to supercharging (not home, destination, or public charging) and even for supercharging an older "A" type battery is also slower, so a newer S60 battery may be just as fast as older S85. As for significant degradation, if it happens during the warranty you are covered, if it happens after, by 2020 or later there should be higher capacity batteries available (today you can upgrade for $22K to 90KWh but prices are expected to drop) - whether you're upgrading because your 60 failed or your 85 failed, either way you're going for a new battery.
It's a cost vs. benefit issue, would you rather have 2012 "A" type 85KWh battery or a 2014 "B" type 60KWhr battery? 85KWh is older, and older technology (slower supercharging), and it's warranty expires 2 years earlier. Degradation doesn't just occur with miles, also with time, and the older battery is more than twice as old. Based on the requirements of the OP, IMHO he should go with the newest S60 he can afford, then find a similar vintage S85 and decide whether the extra range and supercharging speed is worth the price premium. A quick example from CPO cars: slightly lower optioned S85 (no sub-zero) with 70% more miles costs $6,100 more than the S60 of similar VIN (actually slightly newer).
S85+McRed+Pano+Wood+Tech+Supercharging+21Kmiles -price $57,200:
85 kWh Model S P41047 | Tesla Motors
S60+McRed+Panp+Yacht+Tech+Supercharging+Subzero+12Kmiles price $63,300:
60 kWh Model S P43654 | Tesla Motors