After more tests in these days (all on cockatrice) with 1x DTT main and 2x DTT side replacing Leylines i can say again that i'm really happy with the card, when it comes most of the time it can change the trend of the game by itself, and about the discard protection i'm not missing Leylines at all.

After testing for some time the 2x main i switched back to 1x Gitaxian Probe and 1x DTT, but i'm still not sure what to play in the gitaxian slot, i like gitaxian when it comes but with just 1x it's definitely the first slot i can change.

I can share where i'm with my sideboard right now and ask some tips cause i have 2-3 cards i'm not sure about:

3 Defense Grid
2 Dig Through Time
1 Intuition
1 Trickbind
1 Pact of Negation
1 Release the Ants
1 Rushing River
1 Wipe Away/Echoing Truth
1 Polymorphist's Jest
2 Spell Pierce
1 Quicken/Flusterstorm/free slot

A new card i'm loving too is Polymorphist's Jest, and i was happy to see it played on the last 15° list at SCG. A big bonus is that's good against 2 or even 3 hatebears at once, and it works against Mother of Runes too. Some posts ago i was skeptical about playing it for the relatively high mana cost but my tests showed that it can work.
I'm not playing anymore Eladamri's Call cause i never meet Gaddock Teeg. I have one free slot which i fill with random test cards like Quicken (i saw some lists with 1x main, i need to test it). Suggestions are welcome.

All in all i'm liking this deck more than ever, this new card imho has led some fresh and useful meat for our deck.