It amazes me that everyone seems to spend so much on their Vultures. Mine's a dual-pulse affair with C-rated shields and two A0 boosters, fuel scoop, SCBs and A-rated power, distributor, sensors, FSD etc. 16 million CR.
I am, however, about to head on over to Shinrarta to sell it and re-buy with the 10% discount. Cheaper insurance...and I may pick up a Clipper for storage over there too, while the rank limit has been relaxed.
Anyway...yeah, the Viper doesn't have anywhere near the firepower or agility of the Vulture. I like my ships fast, so I've got A-rated thrusters on mine - top boost is 392, which is usually enough to get me out of trouble. You do have to compromise and spend a lot of time tweaking your module priorities for power, and even on a dual-pulse setup you won't be able to use a shield cell while your hardpoints are deployed.
Just remember - as soon as your shields drop, run like hell. The Vulture is a tank while its shields are up, but its hull is made of paper.