Ask a Thief Thread.

this probably requires more information than I'll be giving in this post, but as I don't know, I will assume that this is enough:

the sports day event is coming, and a few days ago, KMS got empress shoulders, making the set even better.

the 6 piece set is, as everybody knows, 30atk and 30% bdmg.
so with the shoulder, I will have a 7 piece set, but the 7th item only grants 15% HP and MP

now back to the sports event; you can get a top and bottom, level 80, that can get attack from the scrolls in the shop.
my current ravenhorn overall is 18atk 12% luk and was wondering if it would be beneficial for me to invest in 15+atk top+bottom combo and cube them for HB+LUK, rather than keeping my overall.

I aim for ~15% LUK on each item, but will settle for 9 too.

in my eyes it is only a gain, but there might be some pros and cons I am not aware of.

thanks in advance

I'd keep the overall (those are great stats already) and replace whatever glove you're using with Dojo gloves. 6 set effect + an additional 15/25% boss damage would be much more beneficial than using a top/bottom set I think.