When you look at burst damage (dps within 1 magazine), then yes it is a nerf. Once you look at dps over a prolonged period (taking in effect the downtime from reloading), it actually isn't a nerf. It comes out to be about the same. From my calculations using two 300 suroses, one with the upgrade and one without, the burst dps against lvl 32 enemies of fast suros is 1339 dps. The slow suros is 1213 dps. Once you look at real dps by factoring in reload, fast suros is 906 dps and slow suros is 913 dps. Keep in mind these numbers do not take the "suros regime" upgrade into account, which you would have with the slow suros, but not the fast. For PvE I would use the slow suros with the perk. For PvP I would probably use the fast non-upgraded suros. For abyss defaint, the fast abyss did 1617 burst dps, while the slow did 1345. Prolonged real dps the fast did 953 dps and the slow did 938 dps. Seeing how you get to choose fast vs slow on this gun without sacrifising upgrades, I would choose fast abyss. But if you are using either of these weapons in PvE, then you are drastically holding yourself back. By my calculations, these 2 weapons do about 60% of the dps of the top weapons (Vex mythoclast, Saturn Rapier, TFWPKY 1969, and a few other scout rifles). If you have to use an autorifle, you should choose vision of confluence against even lvl32 enemies as it does 84% of the damage of the top weapons. Much higher than suros and abyss.