I used to be a field engineer for a computer company. When a customer added foreign equipment to one of our systems and had a problem the standard first answer was it was the foreign equipment causing the problem and we were usually correct. So when I add equipment to my electronics suite, I stick to the brand of equipment I have, in my case Raymarine. I would see if Garmin has something and bite the bullet and spend the money. It will make it Garmins problem if you have any issues in the future. I think you may need to modify your radio station license to add the AIS.
I would agree to this statement, if you can commit to it.
While some boats and customers are able to do this, many are not, for various reasons.
In the case of the installation of equipment on my boat, it came to me with a mostly Garmin electronics suite and a non-garmin (ComNav) autopilot which is arguably better equipment that what Garmin produces. Additionally Garmin (nor any other plotter manufacturer) simply does not produce a product that I can easily use both at home and on the boat to plan/review my routes and trips in a PC platform that takes advantage of the NOAA's free ENC charting; problematically it does not allow any importation/exportation with other platforms. While I still depend and update my Garmin chartplotters as a secondary nav source and for my radar and sounder, I would double check with other actually users what AIS data will come out of them to other systems, if you need to do that.
The other benefit of the system I have is I have redundant GPS sources. If my DC power goes down I'm dead, but if I had a failure of my Garmin system I still have my laptop and the independent GPS of the AIS.
An AIS transceiver is not a magical piece of equipment that one manufacturer has an edge over another. It either sends and receives at an acceptable level and sends and receives over the specified NMEA specification the appropriate data sentences. I DO know from my experience that Garmin does RECEIVE outside AIS data just fine - one issue I did have is that my two chartplotters are connected with a Garmin network cable, and only my chartplotter (4200 series - i know, but olds kewl) connected to my NMEA 2000 network directly immediately showed the AIS - the Garmin network did not pick up that data and send it to the other plotter. This required me to extend my NMEA network up to the flybridge to connect to the second plotter for that data connection. I'm sure I wouldn't have had that problem if I had bought a Garmin AIS. The cost of my network extension did not justify the additional cost of a Garmin product.
NOTE: I looked back at my AIS and the current Garmin offering, and the current Digital Yacht offerings. Most of the older Class B (recreational) transceivers are 2 watt transmitters. Some of the newer ones (Digital Yacht AIT2500 and Garmin 800 AIS in particular) are 5 watts. This won't help your receiving - I would guess you will receive exactly what you have before, but could increase your straight-line visibility a bit. For us, we boat in areas where it is rare we will ever be somewhere our AIS signal will outrun VHF straight line....
When considering a Garmin AIS transceiver it would be important to see what experiences others have getting that data out of the Garmin network...It may be simple, I'm just dubious simply because of how near-impossible I've found it to try to update routes from my PC to my GARMIN chart plotters.
If I were planning a large funded electronics refit, I would certainly consider a suite from one manufacturer; assuming I could find one with the combination of features that fit my needs and desires. Not sure there is, but I'd try. I'm a technology skeptic, I think a lot of it self serving for profit. For example, I'm quickly coming to terms with the fact that Windows Office may be something of the past in my life; going from a purchased product to an annual subscription in the cloud is not my idea of a good consumer purchase - its the same with some of the mapping products out there. I already pay NOAA a lot of dang money to give me updated charts; i actually get chart updates from them WAY more often than I do for the Navionics charts I update annually at a cost for our cuddy runabout.
RE the radio station license; I don't think there is a modification necessary - its the same ship and same MMSI. I don't yet have a SSL for NWD but that is my understanding from the research I have done. Has anyone had actual experience with this?