Re: which set for getting the Brian Robertson sound?
Robbo is one of my very favourite guitarists of all time....
For the first 3 Lizzy albums he played on (Nightlife, Fighting, Jailbreak) his main guitar was a stock Les Paul Deluxe with the mini humbuckers. Sometime around the time of Johnny The Fox he had that guitar converted to full-size buckers to accommodate a pair of original Gibson PAFs he acquired while on tour in America. This was also the time he started using the black LP Custom, which seemed to become his main guitar until after he left Lizzy and reverted to the PAF-loaded Deluxe.
As I understand it, the Bare Knuckle Emerald is intended to recreate the sound of his LP Custom pickups. I've no idea what pickups were in that Custom - I would have guessed PAFs or early patent numbered HBs. Tim Mills at BK must think they were hotter than original PAFs, as the Emerald has a DC Resistance of 10 or 11K if I recall correctly. (It may be though, that he is just going for the "Emerald tone", rather than creating a replica of any particular pickup). As a Robbo fan, I really should try some Emeralds, though I haven't gotten around to it yet.
Much of Robbo's best work with Lizzy was recorded either with mini-humbuckers or PAFs. I think his tone lives a lot in his technique and in his use of the wah and delay (not forgetting the Les Paul + Marshall), but I can get satisfactorily close to it with most of the good vintage-style humbuckers I've tried...
The Pearly Gates set is hard to beat for an aggressive authentic PAF tone.