It's not really an uncommon layout--many older winkeyless keyboards were like that. This layout is popular because of its left-right symmetry. Basically it looks nicer. But yeah, you need sets with 1.5x, 1x modifiers and 7x spacebars. Or also buy tsangan kits.
I've gotten a couple of DCS spacebars in 7x length from SP for that reason. But now my new sets will be ordered with tsangan kits right away
. I would recommend the ''GKH'' gray for that thick PBT set. It's close to the color of modifiers. I have that color spacebar and that pbt set.