Think that 115's are a bit of a rarity, you'd have better luck looking for a 120 set.
TBH, I find the opposite. Dunlop's DBS's have plenty of punch & brightness, as well as longevity. Haven't tried any Roto's for may years, mainly because I used Roto 66's (LD's IIRC) for many years, mainly because at the time, they were the cheapest available, but always found them to be a bit lacking, and they'd not last very long.