Suggestion: Remove Repair Limpets from the Xeno Multi-Limpet Controller, and replace them with Collector Limpets.
Why?
The Xeno Multi-Limpet controller is of very limited use right now. It offers C3 decontamination, C1 repair, and 4 research limpets.
Unfortunately, the C1 repair is essentially useless. A C1 repair limpet repairs at 1.5 hull/second, for 40 seconds, and 60 total repairs(I've tested this to make sure). A C3 Decontamination Limpet repairs at 2 hull/second, for 35 seconds, and 70 total repairs.
This means the decontamination controller is better in both speed of repair and total repair capacity, as well as removing caustic damage, with the only downside of not fixing the canopy(For which they'll have an AFMU anyway), and the repair limpet controller is effectively useless.
The research limpet capacity is also broadly useless, since you can only use one multi-limpet controller, and dedicated tissue samplers use a 7A multi-limpet controller, which has twice the research limpet capacity.
This leaves only the Decontamination Limpet function. However, the Caustic Sink has been released since the Xeno Limpet Controller came out, and players usually use the largest controller they can fit, meaning the Decontamination function alone is not enough to justify using this controller.
Conclusion: The Xeno Multi-Limpet Controller is effectively useless. There is no use case where it would be used where a better option doesn't exist.
What I'd love to see is for the Repair Limpet function to be removed entirely. It's currently the most useless part of the controller. This should be replaced with 4x Collector Limpets. This would mean players could sacrifice repair capacity for the ability to collect thargoid materials more effectively, like after killing scouts.
This would make this controller relatively effective for AX search and rescue, where shields are likely present to prevent most hull damage, and the main thing you need is the ability to remove caustic damage at all, without sacrificing an optional slot for a caustic sink.
If it were changed this way, I'd swap out the Mining Multi-Limpet Controller on my recue python for a Xeno Controller, and use it happily!