Often the data throughput is more dependent on the amount of traffic being forwarded more so than the number of links. In other words, a 3845 has a certain level of data forwarding that it can support, doesn't matter as much number of peer/connecting routers, more so traffic volume that will be passed though it. Of course, everything else being equal, more links/peers might increase traffic load.

A 3845 is recommended for T3s (single one), but they also seem to be able to forward up to about 100 Mbps (duplex).