The backing makes a big difference, yes. I have some tracks of the Shads with Hank taken out of the mix as much as possible, and when using them my guitar sound is incredible. It sounds just like the record and not like someone simply playing a twangy guitar over the Shads. But when I play with produced backing tracks there is definitely something lacking.
Bruce playing Cliff's jangly J200, Jet's dry, flatwound sound and Tony's slick playing on those crisp sounding drums were all just as important as the lead guitar. I'm appreciating that more and more as I listen to the early records. Hank's guitar sound, as much as we love it, was only 25% of the Shadows' sound. And let's not forget Abbey Road's reverb chamber and Malcolm Addey's skill as a sound engineer.
J