SM4,
Yes I agree - RADTAG is a good function. I use it in C as well because it is quick when I need it for low level transits etc.
However, I just know that I will see a lot of aircraft using this service at the same time (as a pilot why wouldn't you!?) and the chance of one of them 'falling off the end of the world' is a very real scenario in my neck of the woods - unless there is some safety net - the only one I can think off is something equivalent to a paper strip / pad (that should give Dick a heart attack!). The left over strip sitting there in the old days has often been a back up that has saved butts - literally.
The compliance with submitting details in to the system is very low around my area. What is more amazing is the attitude from a few pilots who have to wait for a clearance - "whats the delay?", "uh, I just have to submit your flight plan! You know, like you should normally do?!". Never mind the other traffic!
Don't get me wrong, I don't mind doing it, because when I am am flying I like the flexibility of being able to give my details over the air for an unplanned transit through CTA (dodging WX or whatever) - it is a good service - but a little notice would be good, and a little courtesy would be even better.
The problem is probably education - if you think you are going to need a clearance 100nm up the track, then submit your details then, not 5nm before the step - any sector can enter a plan workload permitting. A bit of notice is the key.