The mono-white version of D&T is by far the most popular and well-tested of the D&T variants. The mono-white versions are very well refined and do not tend to vary much; you can take mono-white D&T to just about any event and expect to do pretty well. There is no *need* to splash to be successful. Recruiter of the Guard and Sanctum Prelate really decreased the number of pilots splashing a color, but there are still some reasons to give it a shot.
Splashing a color tends to result in a slightly weaker mana base in exchange for higher card quality. Splashing offers some unique hate cards, angles of attack, and sideboarding options that the mono-white version does not have access to. Splashing often drastically changes matchups, so be sure to test well if you opt to splash.
Splashing does not have to be dramatic. Often a player will splash for 1-2 specific cards, but those cards may be incredibly powerful hosers. Splash builds often thrive in unhealthy or predicable metagames, but are perfectly viable on their own. Splashing does, however, make cards like Wasteland, Stifle, and Price of Progress considerably more threatening.
It’s become popular to splash for Magus of the Moon and/or Orzhov Pontiff in the current metagame. Many decks are doing this largely leaning on Cavern of Souls for fixing. Take a look at the decklists tab for recent double splash lists.
Finally, splashing a couple of cards does not change the archetype. You can splash a few green cards without becoming Maverick or a few black cards without becoming Dead Guy Ale.
” DnT has a huge amount of creative energy being poured into it, and contrary to those who said, “Oh, if you move away from WW to WG or WB, you will just end up with Maverick or Deadguy Ale”, I have to say, it doesn’t look that way.” -Redtwister