There can be benefit with more full range speakers but it depends on the response of the speakers in your room/listening environment and the ability to blend the woofer in a manner that fills in the missing low end without producing excess output at the frequencies the speakers cover. That may require some tricky and hard to achieve crossover parameters. For a more full range speaker, be sure the sub truly can cover the missing very low frequencies down to 15-20 hx or so to start with, otherwise there is no likely benefit save a lot of boomy and poorly defined bass, you know the kind I am talking about, right?
Many smaller and less expensive subs are designed to match better to monitors or other speakers that may only go down to 50-60 hz or so otherwise.
GEtting a smooth blend that truly sounds good can be tricky in any case. That's one reason why educated full range speaker designers make the big bucks! :-)
In general I agree I would start with choosing my full range speakers first and then add a sub later but only one that can be matched well and only if needed, but even then it helps to have the right tools and equipment to measure the results and enable a smooth crossover/blend.
Many smaller and less expensive subs are designed to match better to monitors or other speakers that may only go down to 50-60 hz or so otherwise.
GEtting a smooth blend that truly sounds good can be tricky in any case. That's one reason why educated full range speaker designers make the big bucks! :-)
In general I agree I would start with choosing my full range speakers first and then add a sub later but only one that can be matched well and only if needed, but even then it helps to have the right tools and equipment to measure the results and enable a smooth crossover/blend.