The only sled I can speak for with the valve deletes is a piped 1000, haven't tried them on anything else.
On the 1000 it gave the bottom a tad of a hiccup, but the midrange gain was VERY noticeable.
I think it's worth the tradeoff. I ran them for about 1000 miles, then got rid of the sled. IMO, if nothing else it gets rid of one of the things that's a pain on the M's, the PV cables & servo, one less thing to adjust & a little more weight off the sled.