The T245 clones will have no problem pushing 60W+ with a fat tip. So for a $100 station you've already significantly surpassed the performance of the 40W stations, when we are specifically talking about OPs type of workloads with large surface areas.
That's the rub, I'm not sure the "extra" power of conventional tips are actually making it to the joint (at high enough efficiency). The metcal power meter never went above the level of a fully wetted/molten joint on the plane so I doubt more power = faster, the different tips all pushed the same surprisingly low power into the joint.
A thin copper plane is a bit different than a solid copper/brass EC8 connector. You can watch SDG's videos to see power into a copper coin, which is probably around the mass of a EC8+10AWG wire or so. He's shown power draw in excess of 80W.
Where else do you think the power is going? We know some will be lost in the cable, PSU efficiency, but its not huge, and you can measure those if needed. I would guess its better than 75% efficient.
On the Metcal you have to take into account the RF PSU efficiency, which I guess is in the range of 70-90% on the 5000. Or just use a RF watt meter.
If I measure power at the wall on MX5000:
- 5W idle - no tip
- 90-105W when heating up - depends on tip
- 80-90W with a 2p coin - also depends on tip (STTC-137 2mm, M7LC650 5mm long)
So that means ~70-75W is going into the 2p coin. Much more than into an average PCB plane.
edit: Managed to hit 101W at the wall with STTC-017 (5mm chisel) and 2p coin, essentially maxed out the station. A 2p coin weighs 7g, EC8 connector should be ~12g.