What's the problem with the PSUs? What are the symptoms? Is it something I should watch out for?

As for the keyboard, I like the switches on the keyboard I've got. I find that mechanical switches are too stiff for my typing style. The feel of the standard keyboard certainly requires some getting used to, but after a day or two of light use I find it's second nature.

But if you're not typing long documents then mechanical switches are probably fine. But really, don't waste your money.