Yes it is, Deadly Strike works well with it, I ran deadly strike with Flurry/Bloodthirst shortly after it received it's first damage buff sometime last year. It might seem counter-intuitive since it's a magicka set but a set like draugrkin's grip could work well with Flurry, since each attack is buffed by the set. It would synergize well with some kind of dot based setup, like 2h axe/dual wield axes for bleeds, plus whatever class dots you have (like on a DK), since every dot tick and hit of Rapid Strikes would also get the extra damage from the set. It's too bad it has spell pen on it though since it's a worthless stat for stam
I wouldn't actually use the Rapid Strikes morph though, the 3% extra damage is only a 3% increase of the first small hit, so the overall damage increase with the morph might as well be zero. The Bloodthirst morph actually has a decent heal (still 1k+ in pvp) so it's a much better morph IMO. Also, when using dual wield spammables, it's important to keep the passives in mind (+20% damage sub 25%, +15% damage to CC'd targets) when trying to get the most out of the abilities. CC on an enemy at or close to sub 25% health you a very substantial damage increase from Flurry, enough that you don't really need to run an execute (unless you have a class execute) and can just finish a target with Flurry instead.