+1 On Halcyon not being the only brand. If you're a new/aspiring GUE-diver and haven't yet learned the pros and cons of various DIR-style brands and/or gear features for this style of diving, Halcyon can be great one-stop shopping.
+1 On WKPP not being brand specific other than that only RB used is RB80. Halcyon/DUI gear has a great track record of reliability on the demanding dives and support done by WKPP. Great support from manufacturer for any issues that do arise.
Info on Halcyon SS inflator recall is
here. With pictures showing post-recall SS inflators have a ring on the inflate button fitting and I believe only the post-recall inflators have serial numbers etched into the plastic portion of the inflator. If you still have a pre-recall SS inflator, contact Halcyon, they will support you.
I own at least 9 Halcyon wings of various sizes (and kept in various locations). Only 2 have plastic inflators. All of my SS inflators I exchanged for post-recall SS inflators. I've had more problems with the plastic inflators that see salt water than the SS ones that see salt water. And when I do have problems with an SS inflator, it can be rebuilt*. All the oring numbers/specs and explodeds are in the publicly-available Halcyon inflator manual (kits are/were available from Halcyon). There are no seats to replace in the SS inflator, just orings and loctite.
*Manufacturer recommends these SS inflators be serviced like a reg (= every 6-12 months), when in doubt/lacking equipment-tech experience, follow that interval. Although I know of many SS inflators in the field that have been happy with longer service intervals.