I see it as two different things, the PSU upgrade was actually brought about through a fault in the design, you can think of it like changing brakes, tyres or suspesnion on a car, it will go at some point, if you think it went early do you change the the same OEM part or replace it with a better part designed to do the same job, or even better job but without the dealer margins.
My trusty old E Class has just hit 100k miles, I know the springs will go at some point, will I buy replacements from Mercedes or use it as an excuse to fit some Eibachs?
I am now a year out of warranty so I will fit the Eibachs.
I also have a remap on my car, I remap them all, however this is hardly classed as maintanance, this was me wanting to get more performance out of the product.
It has done that and very impressive it is too, but with all remaps you know the risks, and if the engine goes bang you can't expect the Manufacture to pay for it. Now it may have gone bang anyway, but we will never know and you have to prepared to take that on the chin.
The PSU upgrade is to repair a faulty product, and even if it is done as an upgrade it is not done as a 'hidden from Meridian' upgrade, it will be very obvious, where as the firmware is not to fix broken firmware (shut up at the back!!!

) and could brick your unit, and 'some' may try and get Meridian to pay for that repair.
I am not sure where you stand legally, but if the courts say Apple can't stop end users unlocking their software I don't think Meridian have a hope in hell.
Meridian could start to charge for firmware, even if it was a small fee of �9.99 or something, this would then give them far more rights over copyright etc.
Tag used to and it worked well.
I just don't see how you could fight it in court if you are giving it away free anyway!?