Mike, I've only had 1 IFE (2 if I had someone to declare it to). But if I deem something serious enough to call it an emergency, I'll do what I need to get on the ground and deal with the consequences later.
If given a hold, "unable" would probably be the only thing you would hear from me. On the other hand, is one rough engine in a 421 really an IFE?
Let me give you a story where "unable" just won't work in that situation and you may just have to play ball. Again, the LAST thing you want to do is become a traffic hazard to other traffic, whether or not you're an emergency, and if ATC is telling you that they need time to clear people or work other traffic away in order to get you down, and you just decide to "unable" it and go barrelling down yourself and end up midair-ing someone; then thats inexcusable.
In my situation in Korea, I had a failure of one side of my electrical system while IMC, a definite emergency in that airplane. 80 miles from base, I declare an IFE with the Korean center, then am handed to the approach controller who wants to know the nature of my emergency in more detail. I let him know what I've got, and the potential for further electrical problems, and knowing the WX being ~150-200' and 1/2 mile, the only useable approach was the PAR into the prime base. I'm pretty much expecting to be THE priority due to both my aircraft type as well as my emergency that could very well turn extremely serious. Expecting to get automatically vectored in, I'm instead given a hold, as there are 23 other fighters trying to get in, and I'm
the #7 IFE in progress, the other ones being an F-16 with a lightning strike that has limited electrics who's being led in by his wingman through the WX, 4 others (2 x F-4s, and 2 x F-5s) who are emergency fuel or nearing it, and one other with a hydraulics malfunction. So now my emergency is kind of second rate....I mean, I still have electrics unlike the F-16....though they're not working that good and could go out at any time, but I'm not about to flame out any minute either like the two F-4s, and the two F-5s. So, with all that, there was NO way I could say "unable", as my problems were now minor in comparison with the others, even if I was in the most expensive of all the aircraft almost combined. So, I entered a hold for other emergency traffic to recover, until I could be given vectors to the GCA final controller for my own recovery.
An extreme example, yes, but still one that shows that while you may have used the "E word", it might not always mean that traffic INSTANTLY stops and is cleared for you, and the controllers workload and attention can just automatically go to you. As I said, you've now just
unintentionally become a royal pain in the ass to ATC, especially when there's a combo of high traffic, low WX, and/or other emergencies in progress.
But I think it's equally bad when during normal or say "urgency" situations arise, everyone expects to be treated like the second coming with no appreciation of the fact that the sky is full of hurtling aluminum. .
This is the main point I'm trying to make. The most important thing is both sides keeping the other informed of whats going on and why.