You know what I think
Hi-beams are perfect on there, but are a little lower tension than you might want in .45-.125 guages. Still I think their growly bottom end is the perfect -02 sound. If you add a touch of relief they should feel pretty close to the XLs, but they'll always have a little more give. The low B on the DRs are not perfect, but work well below the 5th fret.
Fat beams don't sound as growly, but are a little stiffer.
Lo Riders are probably the most direct replacement in feel for the XLs, but they are not as growly/grindy sounding as hi-beams. Still a lot more grind than XLs though.
LaBella Hard Rockin Steels have tons of low-mid growl and grunt. I'm not sure if thats what you want or if you've got enough low mids and are trying to add grind in the high mids. Still a great string and the best low B around.
LaBella Super Steps might work well for you. They're more of a high-impact sound like an SR2000 (which are also very good), the downside there is they require a full setup since they are exposed core.
Lets see what else have I tired on there ... I didn't like lakland steels at all, I never found a nickel string of any kind that I liked on it. I'd try rotosounds since they'd probably sound the best of all, but I'm afraid they'd kill the little frets.