To me, the Swift is a swing and a miss.
I have 5 of the regular transmitters. I have never felt any need to use more than 2 of them on one dive. I use 2 when diving sidemount and when diving my CCR. I have never had any desire to add transmitters to my bail out or deco gases. I obviously could have, if I wanted to, since I have them. Even with the 2 transmitter limit, I could have put 2 on one computer and 2 on another (since, if I'm diving with BO or deco gases, I would have at least 2 computers anyway).
So, allowing for 4 transmitters now is cool, but of no perceived benefit - to ME.
EDIT: It IS a benefit that I can now put in the IDs of my single tank transmitter, my doubles one, and the 2 on my CCR and just change which one(s) I'm monitoring, rather than having to re-enter ID #s every time I switch between different rigs that I'm diving. I take back this first comment. I don't see using more than 2 at a time. But, having 4 programmed in will be useful.
On the other hand, the Swift now requires a small screwdriver to change the battery. I have had to make a last-minute battery change before (more than once). Being able to use any old coin to get the battery cover off is great. Requiring a special tool for that would have been a huge pain on more than one occasion. To me, the Swift is a regression, in that regard.
Also, I use 2 transmitters at the same time, all the time, on my CCR. And have used 2 at once whenever I was diving sidemount. I have never, ever had an issue with transmitter interference. I guess MAYBE it could be more of an issue if you were using 4 at once - but, as I said, I don't see myself doing that. And, if it did happen, it's so easy to fix! So, the collision avoidance is cool, I guess. But, again, of no perceived benefit - to me.
With the Swift being $395 and the older style being $350, I will be buying the older style ones until Shearwater no longer offers them. Saving $45 per transmitter is clearly a benefit - to me.
If I do end up needing a transmitter and Shearwater is no longer selling the old style, then I would buy a Swift. The Shearwater warranty and customer service is definitely worth buying a Swift over a non-Shearwater-branded PPS transmitter (to me).