Thanks. Have you actually tried using the ACR? Just curious...debating between that and a 2-way messenger like the Garmin In-reach.
The two items you’ve mentioned are realistically for two separate purposes.
The EPIRB is a dedicated, single purpose, come-and-get-me beacon for life and death situations. If you activate it, expect the response to involve the USCG removing you (and anyone else) from the vessel. They’ll be coming to save lives, not the vessel, and they’re not likely to offer to tow the vessel or give non-lifesaving assistance. The advantage is that in the type of scenario where this response is needed, a properly registered EPIRB is the single most efficient way of relaying your position and distress alert directly to a Rescue Coordination Center (RCC). It’s almost automatic, and gives local SAR assets all the information they need to launch a rescue, with a single user action (i.e. pushing the button).
The satellite messengers, on the other hand, are just that: a low-bandwidth satellite data link that allows you to send texts. The distress function, while included, is not NEARLY as streamlined or efficient an EPIRB. So while the interface (pushing a button) is the same, it may take longer for the distress message and position information to be relayed to the correct rescue authorities in your area, and it may or may not automatically update your position like an EPIRB will. It’s worth a deep dive into the particular device that you’re purchasing to figure out how their SAR interface functions. The advantage to the messenger devices is that they allow you to communicate on a non-emergency basis. So whether it’s just updating the wife that you’ll be out later than you thought, or contacting SeaTow because you’re broken down but not necessarily “in distress”, or communicating a need for specific medical attention but not necessarily an evacuation, you can specify and arrange for the specific assistance you require.
In my opinion, any vessel that regularly travels outside an area where others are visible (i.e. anywhere that a traditional distress signal such as a flare or a distress flag will not be sufficient to attract prompt attention) needs an EPIRB. Personal friends within the USCG SAR and aviation communities tell me that your chance of being rescued after signaling distress via a properly registered EPIRB are astronomically higher than any other means of distress signaling. It’s the device around which the modern SAR system is designed to function, and for $500 for a 10 year unit it’s the cheapest insurance you’ll ever buy. The satellite messengers are a “nice to have” device, but if you regularly operate beyond the range where your VHF can reliably reach shore stations (around 30-40 miles offshore) and/or you operate without a buddy boat or in remote areas away from other vessels, they’re probably worth the addition to your kit. The plus side is that you can also take them with you hiking, backpacking, skiing and in most cases while traveling internationally, and they’ll serve the same communication function.
Sorry for the dissertation, but hopefully it’s helpful information.