The plug popping issue was mostly the '99's - much newer than that and it's kind of a non-issue. Matter of fact, even in the '99's it was pretty rare considering the number of them on the road.
As to avoiding a V10, thats kind of silly. The V10 is and has been an excellent motor, and as of a few days ago Ford announced they are going to offering it in the medium truck market as well, territory previously you'd only find a diesel.
And as has been said, others have come and gone, Ford is the only gas chassis left - there must be a reason they're still here.
I'm not sure where your mechanic was coming from but on this one I think he's a bit out in left field.