so, that is two tickles.
56 damage, let's say 60% fail on dex save; 33,6 damage average.
6 longsword attacks, 69(noice) damage, 60% hit rate, 41,4 damage. That is with normal weapon.
Like I said, fireball ain't that good. Sure, once in a blue moon you will fight BBEG with 50 mooks around, and then it will be great, but most of the time, you are better of spending that slot on disable/utility spells. Something that will be useful at all levels.
Fireball-action surge-fireball is great at 7th level as multuclass, but it fades quickly.