Stupid power supply question (at least I hope it is stupid :-).

No - but each wire and terminal post has an amperage rating.

The multiple terminals allows you to either A: split it to different devices, or B:, what I do, run multiple lower-gauge wire (so instead of 1 x 16gauge behemoth, I run 2 x 18gauge ...) Its about load distribution, not total load - current to a single output will be 'kind of' (there is other things to consider, but practically speaking its ok to use the logic) shared equally the terminals... Its still limited to 25A but instead of all that current through one output (at which point, heat and failure are a concern), you can run 12.25A per 'channel'... or if its like most, where it has 3 outputs, 8.25A per channel. Moving 10A is ok on much smaller gauge wire than 25A (the impact is logarithmic)

Re the second part : No, not at QU-BD loads. The connector combined with the traces are not designed to have 15A (QU-BD + Other bits) running through it reliably.

well - thats the approach I'd take for peace of mind and longevity of operation...  and you'd want to then directly patch the bed heater mosfet into the supply using some short lengths of that wire to bypass the PCB tracks.

Not at all time consuming (prob 10 mins of work) in return for confidence in the equipment.

meh - i just use my hakko knock-off with its usual fine-pitch tip that I have for TQFP work, .1mm fine tip? anyway.. works fine, just use the side of the tip instead of the tip... more heat transfer there anyway. bit of flux and bob's your uncle...

But yes - SSR is less soldering-to-be-sure work, but you do need to make sure its heatsunk still etc and theres another package to deal with and whole seperate power runs yada yada... so its up to you if you mind the trade off of another package and associated wiring to lug around (that needs attention to be over-spec by double or heat-sunk) vs a 'neater' and more compact all-onboard solution.

Both options work as admirably as each other.. its the presentation and additional cost (40-50Amp DC-DC SSR's aren't chump change) vs the soldering work that primarily differs.