So, I got the Driveline 60t chainring on the bike, and coupled with the 11-25 cog set, I think I can now roll at the speeds I want! I've yet to take it anywhere beyond around the block, so nothing definitive yet, but initial impressions suggest I've got a good working range off the big ring now. The 44t inner is still in place, just in case I meet a mountain.
A word on the Driveline: it's not a performance item. It's a hefty chunk of alu, nicely detailed with the machined/polished cutouts, but it's not pinned or ramped, so shifting is old school style; gotta slow cadence and ease up to get the chain up on and on. The old 54t Origin8 was very sweet shifting, so this is a step backwards in that regard, but the fact is I'm almost always on the big ring, so front shifting quality is not so important to me. Still, it would have been nice to get a quality 60t that looked right and didn't cost more than a third the price of the bike!
Hopefully I'll be able to put it through it's paces this weekend. Here's a pic: