We ran in to an issue today after replacing a CCR1009 with this CCR2004 in order to add SFP+ ports.
A while after replacement, downstream users started having odd issues. We quickly found that it was an MTU issue with our MPLS network. The largest ping we could fit was 1450bytes. After pulling some hair out playing with MTU, and upgrading from 6.48.5 to 6.49.1, our consultant looked at another network he helps out with, as they use the CCR2004 in the same sort of configuration. There were only two differences. They were using 1Gb RJ45 SFP modules where needed (we are using tik brand SFP+) and they were running 6.47.9.
We swapped out the RJ45 SFP+ module with a 1G Mikrotik SFP module, and the problem went away.
For the sake of complete information, the MPLS would leave this router on the other side on a 10G DAC cable to a 1036.
There seems to be some compatability issue here.