I agree that a lot of accapellas sound bad
They are very often out of key and which makes you cringe in a club, or when listening to them on tapes, even though you like both the main tune and the accapellas main tune.
I dont agree that the Last-rhythm-Santuary of love mix is an example of that, I must need my ears cleaning i guess but i dont hear any real problem with key, and it would get a dancefloor going mad, which its all about really rather than musical perfection.
I also agree in a way that Last Rhythm should be left on its own, but with an instrumental master piece like that your always going to get accapellas over it.
As for the Belfast-Alright , yes that is good, but imo the vocal isn't one of the most uplifting ones, alright goes over most tunes, without any key problems.
And, btw i rate Belfast higher on my top 10 than last rhythm.