I first read about this "switch" in an article published by a flight instructor that I respect - Darren Smith. One of his popular "top ten" lists consisted of things that can help the single pilot IFR pilot juggle the work load. The article can be found here
Im going to come right out and say that I don't think this is worth the effort and money...
... and I can only say that for myself, you may need to consider where you fly and how the IFR system works in your neck of the woods, but flying in the Chicago area can be tricky when given departures and arrivals.
When flying down to Carbondale, I usually file a known outbound fix - Peotone (EON) and then an inbound fix near Carbondale called Centralia (ENL). Most of the time I get it, and another part of the time, I get "proceed direct Carbondale." This is almost a 250 mile trip. Regardless, the time it takes me to click in EON, then ENL, then KMDH, is about 30 seconds. I dont think that is too long of a time to enter a flight plan. If it takes you longer, then I think time is better spent in practicing entering the flight plan.
Here is a case in point - On my way home from Carbondale, I flight plan for VNN, CGT KIGQ. I always get it. However, sometimes around KCMI, I will get a re-route for traffic flow in Chicago. Sometimes I will get PNT V69 JOT CGT KIGQ... Sometimes I just get JOT CGT KIGQ... Sometimes I get a "proceed direct". You have to be able to do this in the air.
Im not sure what the switch is going to save you.