If you really want him then go and try your luck but have no regrets after doing that and not getting what you wanted to get, of course getting the 40 frags you need .. But in my experience, i spent some couple of hundreds of cps on the Konoha Great Tree last cycle to get my last 20 frags of him and i feel disappointed after getting and trying him .. I can say that go and get him if you have the appropriate ninjas to team up with him, Shisui to be exact or Danzo but if you don't have any ninjas like them then you must reconsider things ..

Yes, when i completed him last cycle, i tried and team up Kakashi[Anbu] with Itachi[Anbu] and Masked Man, using Firemain and Lightning main .. It feels like it is lacking in some aspects and just lacking something .. But i guess if he's with Shisui, the team will be more efficient and more reliable .. Maybe with Danzo too ..

Keep your coupons for now and wait for better Ninjas in next event cycles, you may also end up completing your Kakashi[Anbu] from gaining his fragments for free from the next events ..

I don't know since i don't have Danzo at the first place to test the team but with Firemain, Danzo, Kakashi anbu and Itachi Anbu, it looks like it will work .. or something with Lightningmain, shisui, kakashi anbu and itachi anbu will do better ..