Pots that start scratching within a few months of use. The usual clean won’t fix it and then it needs replacing. I’ve had this on a few modules now and its really annoying. Especially in a situation where I don’t have time to get it sorted and have a show planned. There goes my filter sweep…
One module that really annoyed me hardware wise was Mangrove. The module cannot be tuned without a dummy cable because of an internal offset. This is a known design error. It’s not a huge deal, but in a live setup where nothing is pre patched/need to do everything in a rush, it’s a pain in the ass.
I do not, but I have people who do make modules for a living in my circle and have gotten a ton of information from behind the scenes. It wasn’t something I became interested in until I started running into the issues mentioned above.
W/ was simply not functional for the first months. As much as I love it now, I cannot understand how it was ever released in that state. It would freeze within 20 minutes of use(hard reset needed), recordings would glitch and just end up sounding like harsh digital noise. This was not a case of people trying to break it, it was simply not ripe for public and it took a lot of time before it eventually became functional.
EDIT: This is a good read about the modules from Rabid Elephant. They take good care to deliver something that will last: https://rabidelephant.com/pages/inside