Are your 650Bs actually a limiter? Just pedal harder :)
This is a fair point. Probably makes zero real difference, other on proper hill climbs perhaps.
Currently I use 38/40mm (the specs say both 🤷♂️) G-One Speed (effectively slick) having had enough of Gravel King slicks in the same size.
I think I'll save the cash [edit: or buy a pair of Contis if I suddenly decide to ride up a non-virtual Alpe]