I'm just after some headroom. If I run the rated RMS of the speakers, the amp will be pushing. Rather have some headroom so amp doesn't have to work so hard etc.
I thinking you've missed the mark a little.
My suggestion for the cheaper amp was to leave more money for a better set of speakers, not nessacarilly the ones you had selected.
it's obvious the amount of effort you've put into reading as much sources as you can, but i think maybe you've read
too much.....Looking too much into specifications on paper, rather than considering how a component is likely to perform in the real world.
At the end of the day you want the absolute most value for your money that you can get. Sometimes you have to leave out some of the more technical details, and go back to the basics.
Power is power. Whether it comes from Alpine , Focal, Steg, or something you built yourself, it dosen't matter. The audible differences between amplifiers in any given price range are going to be little if any, and that's if you have the listening abilities to even tell the difference.
What will make the most difference overall is speaker selection, and to some extent the source i.e your head unit. I'm not saying i'm right, or anybody is wrong, i just don't like seeing people spending their hard earned money on something that isn't offering them the most value for their money, and can be better spent elsewhere.
But hey it's your call, if you think the above selection of amps will offer more for your money than a better set of speakers then by all means splash out, it is after all, your money.