Bolo, RMerlin said it best and my prior answer may not be better than this one. I had my problems with Smart Connect, only because my combination of iOS and older Androids didn't play well. In that respect, Smart Connect fought over what did/didn't connect at times but the router didn't grind to a halt nor did I ever had to reboot. I swapped bands, frequencies/channels/settings, saved/logged out and back in. So much has been written about Smart Connect, some makes sense but then everyone tests differently; what works for one may not necessarily work for everyone. Tests we ran with newer iOS tablets and phones always did fairly well with Smart Connect, even when a single new LG phone dropped by for a day, but if older or additional android units were added, particularly off-brand, cheap tablets/phones, Smart Connect became more a headache no matter how much or low long I tried. Several times I thought I finally had it figured out and dialed in, only to be mistaken.
A friend who has only an old iPhone 5, with the rest of the family devices being new Android tablets/phones, swears Smart Connect works fine for him without any tweaking, for about the area I tested, and he used only an extra 2.4 AP in his den, where no one else goes. After going to manual control and ignoring Smart Connect, all bands cooperated. Anything that's labeled 'smart' shouldn't be that difficult to get working. Best guesstimate is to test to see what or if it works for you, and read what everyone else has tried along the way. In the end, YMMV. Hope that's somewhat more helpful than my first answer.