I agree with Screamin86 - it's not necessary however, not running near the recommended stall for the motor will result in a performance hit. What the converter does is allow the motor to get into the power band (typically associated where the cam shaft and the intake pair come alive). Most performance converters advertise a "Flash" RPM. This is what RPM the tranny will slip to before it starts applying power. This RPM is important because this will be your cruising and launch RPM and where the RPM will be once you're back on the skinny pedal.
The down side to running a high-stall converter is (IMO) a decrease in drivability (fuel milage) and make the engine and transmission to work harder than they would with less of a converter. That extra work results in heat and wear for both the trans and motor. Cam, intake, and converter selection should be considered when spec'ing your motor. As the converter, cam, and intake combo gets more wild, understanding the drawbacks may help you make a better choice on the motor instead of just picking the advertised horse power you want.
I had a 69 Chevelle when I was younger and, with a little peer pressure, I decided to go to a cam & intake that recommended a 3300 stall converter (which flashed at 3k). When the Chevelle hit, it hit and was gone when I could get traction. Getting on the freeway was a BLAST. When driving it around town though, I started to not like driving past cop cars and through neighborhoods because my motor were spinning to mad heck and the exhaust was screaming "I AM HERE!!!" even at lower speeds. Gas milage was in the weeds too though I didn't care much at that time.
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