In general, the routing performance of this group is pretty good. (Open the router summary table and scroll to the bottom to see the results summary.) All products measured at least 60 Mbps in both LAN > WAN and WAN > LAN directions, but there are a few oddities to note.
The best overall router was the Ubicom-based DIR-625, which tracks with my experience with other Ubicom-based products. The 625 had 100 Mbps wire-speed throughput in each direction and a total throughput of 144 Mbps. It also maxed out the capacity of the Maximum Simultaneous Connections test at 200, which means it can should be able to handle P2P and gaming applications.
It should be noted that the D-Link DIR-615, although also based on a (different) Ubicom processor and having the same 16 MB of memory, did not perform the same as the DIR-625 in my tests. The biggest differences came in the simultaneous throughput and maximum connections tests.
Figure 1 shows that the router would cut out for seconds at a time, which pushed the total simultaneous throughput tests down to around 66 Mbps.
Figure 1: D-Link DIR-615 Routing Throughput
But, more significantly, the 615 could reliably sustain only 32 connections in the maximum simultaneous connections test. Ubicom questioned these results when they first posted in the charts and said its tests (also done with IxChariot) produced results more like the 625's. D-Link had no comment on the results.
The other odd routing behavior was exhibited by the Trendnet TEW-632BRP. Figure 2 shows an IxChariot plot of simultaneous WAN > LAN and LAN > WAN router throughput over 5 minutes. You can see that the throughput declines steadily and bottoms out at around 20 Mbps in each direction. Other testing showed this was caused by WAN > LAN throughput declining starting after around 200,000,000 Bytes passing through the router.
Figure 2: Trendnet TEW-632BRP Routing Throughput - 5 minutes
Other testing showed this was caused by WAN > LAN throughput declining, starting after around 200,000,000 Bytes passing through the router.