Performance should not be an issue.
As of 16.7.1 you can unlock the ISR4000 series performance shapers with a Boost license.
With Boost license 4321, 4331 and 4351, all will have a throughput up to 2Gbps+
You can't open the cover of a 3845. 3845 has a modular motherboard which slides out of the chassis.
The board is mounted on a metal carrier that contains ejector latches to assist with insertion and removal.
Loosen the two screws at each side of...