Burgess was fodder to Ace according to Blackbeard(someone Blackbeard defeated mid-high difficulty), so Burgess wasn't even close to his captain in strength and i have no reason to believe that someone who got another powerful devil fruit on top of it would have less growth rate than someone who never got a devil fruit over the timeskip, especially when they followed the same adventure and more than likely Blackbeard became much more adept with both his devil fruits, so more than likely Burgess remains fodder to Blackbeard after the timeskip
On the other side, Shiliew was Magellan's equal(someone who low-diffed the entire Blackbeard pirates, albeit off-guard, but you get the point), so it's very likely that Shiliew was stronger than the Blackbeard pirates(including the captain) at the very least until he obtained the Gura Fruit(so Burgess fodder to him too) and considering they followed the same adventure with Shiliew apparently still not being properly integrated in the crew(more like an ally considering Blackbeard said he wasn't fully trusting him), it's safe to assume that Burgess is still fodder to him post-timeskip