It's true that no one is wrong here - I agree with you.Y’all are all talking about semantics. Whatever you enjoy or put up with is relative. Same with don’t want. If it’s a real Merlin or nothing, so be it. It a car motor makes you happy, so be it. No one is wrong here.
However there are some aspects that can be discussed: both in comparisons and in what matters to people.
For example I've never heard any P-51 replica sound like a Merlin P-51 on the ground or in flight. However I personally wouldn't care about that aspect too much.
I bought a ride in a Collings P-51C. If I may digress for a moment, how that came about may be an interesting story to some people:
I was flying a Citabria out of Beverly practicing my acro. None the wiser that Collings was scheduled to visit Beverly. When I took off they weren't there. On my way back I call in to the tower and they tell me I'm number 2 behind the B-17.
Behind a B-17! Wow! How cool is that, I thought.
So I land and see the bunch of planes on the East side of the airport - I need to investigate this! So after securing the Citabria I go over there and there is the B-17, B-24, Stearman and P-51C. So cool - I've never been so close to those planes before so for me this was a treat. You could buy a ride in a P-51C back then for a half hour or an hour. The hour was a LOT of money.
I sat on the tarmac for about 10 minutes and thought it over. I concluded that yeah it was an outrageous amount of money but this might be my ONLY chance ever to fly the plane that I loved so much. Who knows what the future may bring? And this is one regret I do not want to have. I bought the hour ride in the P-51C.
I got the plane on climb out and up to the landing. I did some of my acro routine in that P-51C. I was in no way awed by the plane or in flying acro in it because a) I had been accumulating a lot of acro time and b) the experienced pilot was up front.
I was not frightened that this was the big ol' mean P-51 - maybe out of ignorance (I know there are regimes where it can bite you) but I was very confident. I felt like I knew what to do.
I think about that flight all the time and marvel at the fact that it all happened AFTER I got my PPL, after I flew a lot of hours formation and acro so I could really get something out of the flight. The timing in my life for that to happen was just perfect.
Ok so back to the topic:
The first aileron roll I did in the P-51 was highly instructive. I gave the usual force on the stick that I had given Super Decathons and Citabrias. I was surprised to find that that didn't even get the stick all the way over. I had to push...hard...to get the stick all the way over. So those two acro planes had lighter stick forces - as does my RV-8 - so to me, if a replica has lighter stick forces - i.e. different from the real P-51, then that's a plus for the replica.
It was a Summer day and it was extremely hot in the back seat. I think you may be over the radiator - or near it. And there was no way of cooling off. So that was uncomfortable. More modern replicas may be better in that regard so that your passenger when flying two-up is happier. On the other hand there is a lot more room in the back seat.
It was a C model so my visibility was limited. Much better in the front seat I'm sure. A replica D model would have better vis than the real C but the same as a real D.
It was loud but I have a good set of earphones and I didn't really notice anything unusually loud (maybe I was too excited). And maybe it's louder for the guy in front.
These days some replicas - like the Thunder Mustang, and maybe the S-51 (and maybe the Titan) - out perform the Real Thing at low altitudes (the alts I generally fly). Since they typically (not all) don't have superchargers the replicas begin to lose out as you go up. Even to equal the performance of the real thing at the altitudes I fly would be a plus for the replicas.
Looks sort of matter to me. The closer it looks to the real thing the better I like it. Can't explain why. So the Thunder Mustang and Stewart S-51 win in that regard. My grin would be wide if strapping on a Titan T-51 but much wider strapping on a Thunder Mustang or S-51. Widest, of course, were I to fly the front seat of the Real Thing.
I have read that the Thunder Mustang and Titan T-51 do not have some of the handling gotchas that the Real Thing has. And that the S-51 has similar low speed gotchas, but that none of the replicas will torque roll you into the dirt if you apply full power on go around. That's a plus for the replicas.
I often ask myself the question: "Would I feel like I was flying a Mustang if I flew the replicas?"
Here's the strange answer: The Stewart S-51 would make me feel very close to flying the real thing because it shares some of the gotchas. Strange, huh? The Thunder Mustang and Stewart both look very much like the Real Thing so they make me feel more like I'm flying a Mustang. The Thunder less than the S-51 for the reason above. The Titan less so because it's structure visually deviates here and there.
Sound doesn't enter into it much.
Strictly a personal take. I don't expect anyone to agree with me.