I've had a pretty similar upgrade path: started with Apple aluminum keyboards, then got into mechanicals. I started with Cherry MX Brown switches and then moved on to Topre. If your budget allows, the Realforce is built like a tank, isn't too loud, and feels excellent to type on. From everything I've heard here and elsewhere, also extremely reliable over the long term. I don't know that 45g is more resistance than the Apple keyboard, but there's a lot more travel so hitting a key has a bit more "action" to it. You're not going to hear any "clicky" stuff from a Topre board, except some light clatter of the key popping back up to the top after you let go of it. PBT caps will dampen that a bit, though.
As for the PBT question: switching my Topre Type Heaven from the stock ABS keys to nice Realforce PBT keys had a hugely positive impact on the sound and feel. It all became quieter and less "clattery" to use, and just felt smoother to type on (though some of that might be psychological from the sound). Anyway, if you're going Realforce, you will be getting PBT keys stock anyway, so it's not a question you'd have to address.
