it will hugely increase access times
I disagree. A single disc split into 2 partitions would perform just as quickly as a disc with a single partition in most circumstances except that you have some level of flexibility (or inflexibility depending on your perspective). The disc head will have to move just the same distances as it would with a single partition. The kernel filesystem driver overhead associated with flipping between partitions is tiny to non-existent.
In either circumstance if you keep all your data within your user profile (like all good users should) it makes little difference from a recovery perspective when both partitions are on the same disc. Everything being in the same place is more important than it simply being on a different partition. If you have 2 drives then it's a somewhat different story.