AMCI cards for Allen Bradley

Has anyone used the AMCI cards for the micrologix plc series?
Have some existing machines that have the micrologix 1400 plc and they also have 4 expansion cards. I think 6 is the max for a 1400 and now looking at adding a servo controller. I have read that you can control the Kinetix 300 with the 1400 plc using the message instruction and at this moment not sure which direction would be the best. It appears that using the Kinetix 300 and message instructions through a ethernet connection would be the most logical.
Any suggestions.
I wanted to swap them out with a compact logix but due to cost not something that can happen on these machines.

Yes, I've used their stepper controller module (open loop) for indexing a couple of times, worked fine. They've been around a while.

It all depends on what you're trying to do. If its just simple indexing, adding the AMCI module allows you to keep your existing I/O. Personally, I would shy away from the messaging to the Kinetix unless I had absolutely no alternative.