We tested all lineup routerboard for work with IPSec and we have the table with throughput if I can interestingly lay out the reference.
That that I remember on memory so it:
1 - RB1000 - it is very good ~120Mbit as upload and download
2 - RB 600 (powerpc pcu) - shows good results at upload ~16Mbit, download I do not remember how many more low.
3 - RB 4xx (ah) (mips be) show good result at download ~ I do not remember how many but it seems 10-15Mbps, and here with upload works worse from 1,8 to 6 Mbps depending on model.
If I can interestingly lay out the reference to full testing of models