The LDC XH would work with any of the baits you mentioned. It's a very versatile rod. I had Powells, Dobyn's, Shimano's, Loomis and finally settled on LDC's. By far the best swimbait rods IMHO. A lot of members here will agree.
Water temperature affects buoyancy. There's a big chance that a super slow sink bait that was tested in the summer would float in the winter. Also, like someone mentioned earlier, the sink rate would be different if the bait was tested on a flouro line. Did you change anything on the the bait e.g. the hooks and split rings? Does the bait float while deadsticking or on a retrieve? Slide swimmers rise up on a retrieve.
I hope you resolve your issue. I've never had any issues with any of my transactions in the black market. I'm lucky I guess.
I want to see this..cast able?
I've been toying with the idea of trolling a huge spread in the fall/winter really slow. The old school dudes used to whack em in the early days...
The LDC XXH can cast it without any issues.
I have the Picasso Extreme. The wires are the beefiest I've seen although the swivels needed to be upgraded. I rig it with two rising sons and a BA. I haven't had issues with it yet.