Re Dante: Well I have to admit it is very creative, however he could potentially change the entire basis of the Grail War into less of a battle royale and more of a race to the finish line... but that's good actually, it could provide a fresh new spin on a familiar format.
Of course, there'd be the issue that any pagan Servant (and by default most Masters) wouldn't be able to enter Paradiso, unless maybe they forced their way in or something (which some definitely could).
If anything, my idea for Dante just had him with Noble Phantasms vaguely resembling his three guides.