Seems to me we had some posts (or maybe it was PM's) where the front carrot was molded in HD and the back was molded in regular...so that the tail would stand up (float) and the front would sink...but even more importantly...be more durable.
It would work the same was as the "back slide"...but then...any bait can work this way if you put a small split shot against the hook eye!
There was also some discussions about how much HD to add to get the same sink rate as a Senko (Bill posted some data) and what if you just wanted a slow fall on the Freedom Fry. I made some Freedom Fries in 3 "sink rates"...floating....HD (2 tablespoons per 4oz) and "slow fall" with only 1 tablespoon per 4 oz.
But...one of the reasons I got into making my own wacky worms is because I want them to FLOAT when the bass throws them and I go net them (with a long handle aquarium net) and re-use. I use the 2 tablespoons/4oz not only for the fall rate...but more importantly to me...because it makes them significantly more durable (there are multiple threads discussing this) and I can get up to a dozen bass on one Freedom Fry!
So...I have since gone to only floating and sinking/durable and haven't made many more "slow falls" because they were not super durable, did not float and I was getting only 1 or 2 bass per bait before they got thrown off the hook. I really try not to leave discarded or thrown plastics in the water if possible because of (and we discussed this a couple months ago) fish and other critters could eat them and cause health issues.
Andy