Blunt is perfectly fine with me.
I would not exactly agree with the analogy (I drive manual transmission vehicles every day BTW and have for most of my life ).
My point was all about safety margins and that if something fails will it be on the board or on some external (cheaper to replace) device?
And as you said, you are not even using the same board.
The larger power connectors on the stock FT-5 controller board are rated only to about 16-18 amps (on a good day with a full moon and favorable breezes).
The smaller ones are only good for around 8-12 amps.
And that is if you can verify who made them and to what specification.
That also assumes that the wires are inserted correctly, that the connector screws are tightened properly, that they have not worked themselves loose due to thermal cycling, and on and on and on........
So many factors that can go wrong.
You are however quite correct that at 24 volts they should be "OK".
You will get no disagreement from me on that.
At 12 volts however, as the vast majority of these kits were shipped, they are definitely not.
Unless something is done to increase the airflow across the board and its connectors though they may still be marginal even at 24 volts.
You have done that. So have I of course.
But when giving advice in an open forum, improved airflow is not a "given".
Do you really trust a lowest bidder manufacturer somewhere in China that is not even open source with no published specs or parts lists (check the various wikis on them) to provide MOSFETS that have low RDSon consistently?
The high power connectors on MOSFET and SSR external modules are easily capable of handling several times more current than the on-board ones with far less fuss.
They can accept fork or ring terminals for example.
And they can be tightened and/or torqued with reasonably sized screwdrivers (as opposed to the jeweler's screwdrivers required for the on-board ones).
Of course for mains-powered bed heater versions that much is a moot point.
As for the hot end heater, true it only draws a couple of amps at 24 volts.
Actually I have a 60 watt heater in mine so it draws around 2.5 amps.
But I still trust the connectors and heat dissipation on an external MOSFET/SSR module much more than I do either of those things on the controller board.
It's just my opinion based upon similar things I have seen get hot and melt (or worse).
But if everything is done correctly and checked every so often, you are quite right that the board itself is "OK" for the hot end heater at 24 volts.
We have smoke detectors in pretty much every room of our home (beyond legal requirements). Why? Better to be safe than sorry.