I swapped out the stock CMD4a to a CMD5. I'm sure most wouldn't bother, but I found a pretty good deal on a refurb, and wanted a few of the additional features that the CMD5 offered knowing that all existing CeNET periferals like the satellite radio and wired remotes I have also work with the CMD5 (and do not work with CMD6 or above). I also have a use for the CMD4a on another boat, which helped make it worth it to me, although I understand I could sell the CMD4a used on flea bay and recoup about 2/3 of the cost of the CMD5 refurb. Not sure it'd be worth it to others, but wanted to share that it's a fairly easy swap. Both units use the same harness connectors, CeNET plugs, and antenna connectors, although they are in slightly different positions. Even existing helm mounting holes work for the CMD5.
The CMD5 is a bit longer due to a massive heat sink protruding from the rear, and some harness cabling had to be moved slightly to accomodate the unit. Gotta add that because of the location FW chose for mounting the CMD4a on my boat, if I didn't have the tilt steering wheel option, I wouldn't have been able to get the CMD5 installed without pulling the steeering wheel.
I'm not sure why the CMD5 has such a large heat sink when the CMD4a has none. I did notice that the CMD5 is 4 x 21W/channel RMS where the CMD4a is 4 x 19W/channel, and the signal to noise ratio is much higher (91db versus 80db), but would be surprised if that's enough of a difference to warrant such a massive heat sink.
I had let my Sirius subscription (I mean 3 month trial) expire, so can not comment on transfer of Sirius satellite radio subscription between the two head units. I think that there's a subscription code difference, I may call in and try to use the 3 month free coupon I got when I bought the boat a second time.
