Very true, people perish from exposure. When comparing the TheMightyHobie18 to a N20, the advantage of an N20 is it is much faster, making your exposure smaller. The faster you can get in and out the better it is overall.
This is why faster is better for something like this. The faster teams will be less exposed, because they will finish the crossing in a much faster time.
I don't believe exposure is the issue when all is well and either boat/crew is performing optimally. An hour or few difference is all we are talking about.
However, when either boat/crew is disabled, the exposure/survival issue progressively gets more critical.
At best, rescue resources will be limited. I wouldn't count on the organization to be able to provide much. USCG will do whatever is within their capability, but keep in mind that if conditions are bad, there will be more than one of you needing assistance and there will certainly be non-racer related missions that the Guardians will be attending to as well.
An EPIRB might be more useful than a VHF, but the VHF will be handy when rescue is nearby. Only the Coast Guard will be able to receive the EPIRB signal however. Chase boats would not have locating abilities.
A tough and unsinkable boat makes more sense than a fast complex boat IMO.
A few things. Don't discount exposure issues even when things are going "optimally". Over that distance fatigue and even a little chill, small cuts, a little sunburn, etc. grow in significance. And if you've been out there longer before things go bad, you're starting from a more weakened state. Take into account how one can handle the situation if the other is disabled. Not turn anybody into worry bags, but simply things to consider.
An EPIRB/PLB (one for each crew, on their bodies) is essential (required for this event I'm sure), and if you can't raise anyone on the VHF (one for each crew, on their bodies) you'll need to trip it. You need to register the unit providing contact info - that should be the race officials, and when they are contacted they should be able to get coordinates (which may be old, but can provide the race folk with a starting point to search for your bodies). That having been said, you must be willing, prepared, and able to do as much as possible for yourself and your crew before setting it off. Comments about you not being the only one in need of help if things are bad are spot on. Hopefully a forecast window will be analyzed to minimize that potential.
I'm guessing that over the distance, the difference in finishing time between an N-20 and H-18 may be significant, depending on the conditions. I've owned both (and others), and I have to say at this point I am pretty impressed at what the N-20 can take and do. So, if I were to do this event, I'd take tough, unsinkable, AND fast, thank you. But maybe chasing in the F-27 might make more sense...
