We have a CSS610-8G-2S+IN and would like to use a 1GBASE-T SFP module in one of the SFP+ slots. Is this something that should just work? Is there anything to think about when choosing the module?

Product page lists S-RJ01 as "related product". I read this as official supported combination.

I'm pretty sure there are 3rd party RJ-45 SFP modules, but Mikrotik will not list them as working, so you'll have to trust seller on this. Sometimes new release of software (SwOS in your case) breaks what previously worked , in that case you're SOL (if you use MT's own module, you can rightfully demand them to fix the problem).

It works fine for me, this switch accepts all kinds of generic SFPs (and SFP+) I have and work reliable, no guarantees ofcourse with third party accessories. The only issue I found has been overheating with some generic 10GBase-T SFP+. Make sure it is updated to the latest FW version.

It works fine for me, this switch accepts all kinds of generic SFPs (and SFP+) I have and work reliable, no guarantees ofcourse with third party accessories. The only issue I found has been overheating with some generic 10GBase-T SFP+. Make sure it is updated to the latest FW version.

Yeah, we had a FS 10GBase-T SFP+ adaptor flake out after a while, which might well have been heat - they do get jolly warm.

It is known that 10Gbps RJ45 SFP+ modules generate a lot of heat ... the 1Gbps modules (or even the 10Gbps ones when operating a 1Gbps ethernet link) are running much cooler.