I'm not sure I'd agree the Dex 5 is that much better than the 5. I know quite a few people who have reported they'd go back but are now stuck. The other advantage with the 4 is that you have two options Animas Vibe or Tandem Dex, whatever it's called, that come integrated with pumps.I'm a big fan of that. I get decent results from Medtronic Enlite sensors. If you used the Sof Sensor Medtronic, with the big, wicked nasty harpoon needle, the Enlites 1) work better and 2) insert better. I did a very short run with Enlites and Dex 4 side by side and found the Enlite generally a bit more accurate than the Dex 4 but it was a short sample. I started thinking I'd take notes but that lasted about 2 days. I hate logging.
I like the Tandem Dex combo a lot. My local buddies @Phyl arranged a meeting with @Wiffy and I and the Tslim salesperson about a year ago and I thought it looked really neat but I'm sort of a "don't upset the applecart" guy and decided to pass.
The main marketable appeal of the Dex5 seems to be no receiver but when I used the Dex, the receiver was very unintrusive, easier to use than my phone as it has no distractions "ooh, email!" and fits very easily in all of my gear. I am somewhat skeptical that the Dex5 is significantly better, although I have been skeptical of the general assertion that the Dex is much better than the Enlites, based on my N=1 sample. I've run into a few other Enlite partisans who have mentioned "yeah, it works fine for me..." so it may be a YMMV thing? I definitely prefer the fact that Dex lasts for 3ish weeks. That is very handy!
I also agree there are a lot of interesting things in terms of new equipment rumors on the horizon. The FDA process is so convoluted that the companies can only talk in very vague terms about what might happen and it makes it very hard to be super enthusiastic about any product because you could be surprised by a newer or better one at almost any time! Good luck with your search!!