I have both GG fixed length and the TI Goat adjustable poles.
Personally I prefer the GG poles. Simplicity is one reason, but those great "shaped" grips are the other reason.
I have arthritis in my hands and I dropped the TI poles regularly, like once a mile or more, due to the poorly shaped grips. This is never an issue with the GG grips.
Fortunately I fell and landed on the TI poles breaking one top-section. DJ sent me a replacement section (I paid for it since I broke it and don't consider it a defect) and included a free set of straps which makes the TI poles usable for me. I imagine the design creates a stress riser right at the rubber expander, making that a likely point of failure.
The TI poles are only used for my summit attempts when I need poles for the approach but need to collapse and stash them when climbing.
If GG does introduce an adjustable pole I'll certainly get a pair and sell the TIs.

