In theory, yes, they both use the same family type of CPU only a little bit slower clock-rate (and a bit different chip specifications). But 680Mhz vs 600Mhz isn't that much of a difference. Then again, I have heard the CRS125 is not AS FAST as say an RB2011 at everything because it's meant to be a switch, but I don't see a technical reason why this would be true.
In reality I believe it will work fine. I have used a CRS125 up to 100Mbit (very light config) or 50Mbit (Queues, etc.) without problems.
Final answer, should be no problem at all.