No way of knowing without listening to the speakers in that space....Not sure what you mean by “suck it and see” but I’ll assume you mean “try”. I am using Dirac. After replacing the center speaker, the LR might need to be replaced or might not as you mentioned. Will try it out, but first I need to choose a center.
In an echoey open floor plan with 10’ ceiling, which would be the best center speaker within a +-20 degree listening window?
Speakers have always been difficult to subjectively characterise - you can measure them and get an indication of quality, but ultimately they have to be listened to.... of all the components in our setups, they are the most imperfect / flawed - few speakers achieve less than 1% distortion across the frequency range, even very highly regarded ones.... so acceptable speaker performance, accepts flaws that would be grounds for outright rejection in electronics....
The flaws are often resonances - and some people are very sensitive to those, others never notice them.... resulting in speakers being very much a matter of taste.
That makes things even more difficult in the age of online shopping.