I think I'm going to end up a bit of the contrarion on this one.
Gunbarrel: I honestly don't have a strong opinion. I loved the "cold" openings of all three DC-Bonds, though I'm not sure it completely works at the end. A knock-down last scene (CR, SF) with a blast of the Bond theme works just as well. I also don't remember when a bad film has been saved by the gunbarrel. All of Brozza's (except DAD) were great, but to be frank they won't make me watch TND, and won't make nearly everyone else watch TWINE! But, in the interest of "Peace in our time" - let's get it back at the front!
As for the theme....well, see above. But....that's providing it hasn't been used to death in the preceding 2 hours - most certainly the case with the two examples used. I do feel that Arnold's scores pre-reboot, ended up just blasting the theme at nearly every opportunity (what was it Jim said in his great 007th Minute Series "Look at me, I've got the theme"?).
I know most people don't agree, but I liked Newman's use of it in SF - a couple of killer moments (the reveal of the Aston and the red leather door), and Arnold in CR and QoS, just echoes of it at certain moments.
One of my favourite Barry scores is OHMSS - and with the exception of the PTS introducing the new actor, I think the theme comes strong just the one time - when Laz is sliding on his front. As the rest of the score is brilliant, it doesn't bother me. A bit like the gunbarrel, a bad score is a bad score - using the theme isn't going to change that.
So there's my contrarion view - not wedded to either! Start chucking stuff at me when you're ready.....