Theoretically, the resulting bandwidth will be roughly the same no matter where the 4 channels are connected. The main issue is, and has always been latency. If you have a task that thrashes the local L3 heavily and makes a LOT of memory read requests, it's going to be impacted by the latency of distant memory requests. For tasks that tend to be very bandwidth sensitive, that tends not to be the case (yes, there are outliers) as they are most interested in getting blocks of memory quickly.
Where this will likely be most noticeable, outside of synthetic benchmarks that zero in on the issue, is in games that are very system latency sensitive. I imagine that TR2 will still have some sort of gaming mode just as TR1 had to address those situations, though, it rarely made a huge difference when the software didn't have a basic compatibility issue.