I had issues with 10G copper SFP+ modules even when there was only one installed in the switch (Mikrotik CRS305-1G-4S+IN), the other modules installed being DAC/fiber. I got random disconnects I could not attribute until I checked the switch logs - the module was shutting down because it was reaching >90C when the ambient temp was 26C. I had to add a fan.
Not all transceivers are created equal; some need more power (and then dissipate the heat), some are satisfied with less. Some can do only 30m distance, others will run over 80m distance.
The Mikrotik ones (S+RJ10) are based on Marvel chip and they are the more power hungry / run over 30m only variety. On the other hand, they can negotiate 2.5G or 5G if necessary and support a proprietary protocol to tell the switch about it, so you will that in SFP+ properties.
As I have written in the sibling comment, I have good experience with BCM84891-based transceivers. CRS305 can handle two (still not next to each other, obviously).
