Sony Vegas : Reduce Interlace Flicker, any downsides?

[Xirix]

I do a lot of things with video game footage through Sony Vegas Pro 10, I recently found out that Disabling Resampling is a smart thing to do (after seeing that the default Smart Resampling was blurring certain bits of footage something awful), I was also told having Reduce Interlace Flicker on all the time is good.

I tried a render with it both on and off and didn't see any difference, I suppose because it was a progressive capture from my Xbox 360 and would only help footage that's actually interlaced... like from the PS2 or whatnot, I just wanted to check to save any headaches later, are there any possibly downsides to having this option checked all the time?

[pandy]

reduce vertical resolution - IMHO OK for interlace video, not recommended for progressive video.

[jagabo]

Interlace flicker reduction works by blurring horizontal edges. You should not use it unless you are producing interlaced video or watching on an interlaced display.

[Xirix]

Ah okay, so I should only do it for older console capture that's at 480i or 571i (or whatever the PAL is, I forget), gotcha.