According to the fellows who make the rat impulse, a vff provides about 90% of the benefit of an LPR. Of course, you can't adjust your bolt pressure with the vff the way you can with the LPR.
When I added an LPR, I can't say that I saw any noticeable reduction in kick or increase in consistency. The thing that the LPR did do for me was increase my efficiency. All things considered, I don't think I'd add an LPR if I had to do it all over again.
Best bet is to either add and Eclipse LP valve, or have a custom upgrades team tune it for you with an LPR. An LPR needs adjusting so its at the very limits of pressure reduction without depriving the marker of its propellant/air source. Also, don't LPR's on an Impulse fit on a modified valve cap, with a hose connected to a modified tapeworm. The modified valve and tape worm both have air ports in the end for this mod, and can be obtained from Eclipse as an LPR kit.
Need to try a marker before u go spending, in case its not what u want .
I took my marker to SP and had them give it a good old tuneing, has the LPR fitted and im selling on the full flow ,ibut now its running like a bute, rapid as fcuk, campaign here we come, TASTE THE PAIN-T