I'd say Fat Beams are thick and clear, with some stainless crunch up top. They have lots of "life" and punch without sounding harsh at all, at least IMO. I like other DR types too, like Sunbeams and Pure Blues on J basses. I've never tried Hi-Beams, but I'm sure I will eventually.
For tone, I thought nickel Lo-Riders were fantastic on my old L-1500, but due to finger issues I stick with the more flexible round core variants now.
Totally understand the round core variants. Super stiff strings (hex core rounds, chromes) just really turn me off.
Sounds like I'll check a set of Lo-Riders next. Thanks!