For 30 years Mountain bikes all came with disc brakes and QR 
. There’s nothing wrong with QR. it actually has higher tension than thru axle, but TA helps make the frame a bit stiffer. On road bikes it is pretty much just marketing which has shifted consumer preferences.
Some wheels are convertible between QR and TA, it really depends on the hub. Google it. If they are convertible and you can find the caps, then that’s a bonus to the SL5 since you get some nice wheels.
If you don’t care about resale value (will this eventually become your rainy day or trainer bike?), then that’s less against the SL5.
But you will be more limited for tire size, which is a big deal to me. I like to run tires that measure about 30mm. It’s not clear to me how much margin is in that 28 mm official tire clearance. Sometimes that number is conservative so that most tires labeled as 28s but measuring wider still fit. Sometimes that is the true width limit. Do your research.