Well, I use maddmann and CCM springs...
CCM springs are softer than Maddmann's softest. In fact, depending on the hammer and valve, you may not be able to reach chrono speeds over 250.
I know my FPS on my most recent sniper build couldn't exceed 253 when I was running CCM springs on a stock hammer and Tornado valve.
When I install the FreeFlow hammer, I'll let you know whether it's up to speed or not.
That being said, Maddmann's softest are just tense enough to reach 280 without a hitch on many valves including AKA, PPS, Supercharger and the Rocket valves.
The maddmann springs (softest, still) do make for a heavier/tougher pump stroke, but not by much.