Sep 3rd 2008 2:08AM I understand that these comparisons are based off of the Vengeful Gladiator set, but if you're like me and didn't hit 70 on your rogue till around the start of s4 (and thus farmed 5/5 merciless, then began upgrading those pieces to Brutal gear), the Gloves are actually one of the worst upgrades. While the vengeful helm/chest/legs all have a decent +12 hit rating, the Merciless set lacks a single point of hit rating across all five pieces. PvPing with less than 79 hit rating is like asking to lose matches due to RNG; your special attacks will not be capped, meaning a crucial kick, blind, kidney shot, etc. could miss, possibly costing you the match. A rogue in full pvp honor gear (no vengeful/brutal legs/chest/helm) will not reach this hit cap, short of gemming for hit (which is undesirable). Before buying my brutal gear, I had to use my Ring of a Thousand Marks, and before that, even my god-awful violet signet.
Anyway, point is, getting 79 hit rating is really really important for pvp. the brutal gloves give 0 hit rating, so if you're not hit capped on your special attacks, it's definitely better to save for the helm, chest, or legs. (not to mention those 3 pieces all have 84 armor pen, which is pretty nice too).
Even if you are at 79+ hit rating, it's still worth considering; rogues with Heightened Senses and mages with (maxed) Arctic Winds have +4% and +5% chance for you to miss, respectively (though the rogue's is only relevant for Blind); hit rating is also beneficial for higher and more reliable white damage and more poison applications.