KBG pros are it self repairs quickly. It spreads through underground runners (rhyzomes). This can also be a con, because the same runners is what make KBG spread into flower beds constantly. Depending on how many flower beds you have, this can be a considerable con. Runners go roughly 6" deep, so decorative edging won't stop the grass and 4" steel edging isn't deep enough.

KBG uses more water than turf type tall fescue (TTTF). KBG is more disease prone than TTTF. KBG grows faster than TTTF and needs more mowing and taking care of.

TTTF has come a long ways in the last decade. TTTF has much finer blade than older varieties and looks very similar to KBG. TTTF grows in clumps (field fescue is typically the round clump you'll see growing in KBG). It often needs to be over seeded occasionally to help it fill in.

Basically, the pros and cons need to be weighed. Both are good options, but your situation are what should be considered.