And why is sub-5G interesting, isn't the performance end of ethernet at 40G/100G since years ago?
This doesn't really matter in data centers and backbones (which is where you see 40G/100G), but it can be useful in access networks (offices, classrooms, etc.) where the business doesn't want to replace existing cable plant.
Any reason not to use larger channels on 5GHz at home? I can generally only see 1 or 2 other 5GHz networks indoors, compared to dozens of 2.4GHz networks, so SNR should be no issue on a larger channels.
But maybe you were referring to high density enterprise deployments?
Larger channels can be fine at home. But only if you ensure there are no neighbors that overlap with your range. Keep in mind that as you grow in channel width, you'll need a better SNR to maintain those top data rates.
The one other issue I can think of is auto-channel on a neighbor's 802.11n router. An 802.11n router might not recognize the 80mhz channel used in your network, and thus pick a channel that overlaps.
That being said, I use 40Mhz channels at home with no noticeable issues.
https://en.wikipedia.org/wiki/2.5GBASE-T_and_5GBASE-T#Histor...
I would not expect much/any existing 10Gbit hardware to interop.
These days I honestly wouldn't recommend going with multimode for anything new. Use twinax for short distances (e.g. server to ToR) and SM for everything else. The price difference between SM and MM isn't really worth it, especially when taking in account the fact that MM cables usually need to be replaced on each generation.
Though, do you have experience with these exact modules? I have a bunch of “generic” or “cisco compatible” TXVRs died on me recently, some of them became rx-only, some completely unresponsive.
Still alive are finisar-made (or re-branded finisars) and avago. So I prefer used fini/avago to brand-new “compatible” parts.