I recently purchased & configured an MT2500A Router. Running it in Router mode and pretty much idling (doing basically nothing - I haven’t even configured VPN yet), I find the unit to run very warm.
And for others reading this, I do recommend paying a few extra dollars for the Aluminium case version (ie, prefer the MT2500A over the MT2500) for better heat dissipation and hopefully a longer life.
Even so, I’ll have a standby MT2500A unit ready just in case of failure. My MT2500A sits in between my LAN (192.168.0.0/24) and my WAN (192.168.1.0/24), and I don’t want to scramble with subnets if failure occurs.