You're not talking about the Sampras of 2000 and on, are you?
No. I'm talking about Roger Federer. When these two were in their prime they needed to go through peak Federer if they wanted a Slam. Hewitt was actually a better and more complete player than during his time at #1, he just got consistently overwhelmed by Federer. Safin became a multi Slam winner the hard way beating peak Federer. There was never a harder period to win Slams for the average player as the 2005-2009 five year stretch (in 2004 there was an opening on clay with Nadal not yet peaking). On hardcourt and grass, you had Federer playing at arguably the highest level ever on those surfaces and never ever losing early, if you wanted a Slam you had to go past him. On clay, you had to go through Nadal - also widely considered the best player ever on the surface. For a while, you had to go through both to win a Slam on all surfaces (although mostly on natural surfaces). Right now you have a Federer who's on the wrong side of 30, Nadal isn't the same he once was either; Djokovic's emergence was spectacular but he's still way more beatable than Federer ever was in his pomp, especially on natural surfaces.
There's no way that's true, especially now. Murray's forehand is much more of a weapon and is equally effective when counter-punching.
Every other point you have made is debatable, besides mental strength.
Sorry, but that is delusional. I refer you to my response above.
Although I greatly disagree, if they are 'debatable' that's enough evidence that Murray and Hewitt are pretty comparable players qualitatively.