I think that Mrs Grace has been really rather churlish.
Of course it's not a real Spitfire, of course it doesn't come close to the handling and performance. It's pretty close to it visually, but scaling size and weight and using a modern engine clearly didn't allow them to do an exact copy - scaled or not.
I don't think that anybody's ever pretended otherwise.
But the people who have built them have put a massive labour of love into that, and the people who fly them - often the same people - are getting enormous pleasure from flying the nearest they're likely to ever get to a "real" Spit. Plus it gives much pleasure to the rest of us who like seeing a really beautiful aeroplane - which it is, and it's a heck of a lot more interesting than buying a PA28. There is much to be admired in it, and if part of that is the association with the iconic aircraft that it is a tribute to - why the heck not.
G