I have the HA Successor. I use it as a drum bus for drum machines and I also use it as a de-esser for vocals. I don’t have much to compare it to except the Bugbrand StereoCompress, but here is my quick pros/cons
Sound - It has character, but it’s a compressor so don’t expect it to be drastic.
Simplicity - most of the controls are detented (not continuously variable) so its range is focused allowing you to quickly dial in some thump
Blend wet/dry - allows you to bring back some thump if you totally squash something.
Sidechain Filter - Has unique settings, like the mid hump and the high shelf. The hi shelf is great for de-essing. The other settings work as intended. It also has a side chain input but I haven’t used it.
Price - pretty affordable for how good it sounds. But again, it’s a compressor so don’t expect massive change to your sounds - you can expect a noticeable improvement in clarity and depth though.
Make-up gain - is a little noisy (but not bad) this maybe the source/contributor of the character from the transformers but I’m not sure really - it’s not really a con, but be aware it isn’t dead silent.
Power supply - external brick, switching type. This is probably why this is more affordable, and may be the cause of the noise floor on the make-up gain.
XLR in and out - You’ll need 1/4" TRS to XLR cables to interface with a patchbay or interface.
In summary, HA Successor is easier to dial in and has a much lower noise floor than BugBrand StereoCompress.