Having worked on porting OpenWRT on managed switches using RTL8380 SoCs (Support for RTL838x based managed switches), my experience is that all vendors including premium vendors like Cisco use the same switch designs made by always the same Taiwanese companies for these SoCs. Whether the electronic components are of higher quality in some cases I don't know. For a list of vendors for this SoC type see e.g this interesting list:
https://packetstormsecurity.com/files/154201/Realtek-Managed-Switch-Controller-RTL83xx-Stack-Overflow.html
With regards to heat: There are web-managed switches with up to 52 GE ports that do not need fans, for example the DLink DGS‑1210‑52. Fans come into play when either PoE of more than about 100Watts is made available by the switch or there are Multi-Gigabit ports in the switch, as the power consumption seems to increase roughly linearly with the speed of a port. There is experimental support for OpenWRT for switches with up to 28 ports, including 4 SFP ports for fibres with the RTL8382M SoC, all fan-less and some with 100Watts PoE.
Kobi
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