weight?
And also, something that’s always confused me is that it’s seems common practice to search for the lightest setup shaving grams off components where ever possible, but is that all negligible if you’re a couple of kilograms overweight?
There is no simple answer.
I would say 1kg is 1kg it matters not where it is. If you and the bike are 100kg reducing it to 99kg will get you up a hill 1% faster and make no difference in the flat.
However that doesn’t stop some people really caring about how bikes feel. They like the slight extra acceleration of lighter wheels etc. It’s their money so why shouldn’t they.
Time still tell which camp your in
I can’t tell you which bike to buy. But if you’re really new to this are you sure you’ll only ride on the road and never go on over night trips? The bikes you link to are great for unloaded day rides. Other bike bikes will deal with luggage and rougher surfaces better. Thats not suggesting road bikes are bad just task specific