I have two Lelo toys. The Gigi and the Smart Wand (MEDIUM) and so I cannot tell you how the Tango compares to the Mia. Sorry :( (I want to get my hands on a Mia myself, to compare and contrast) I can tell you this, it is more powerful than both of those Lelo toys I own, this is also because the stimulation is more pin point too, but mainly, it is just so much deeper and rumbly than the lelo toys I tried.
The Tango has, probably THE deepest vibrations from literally every toy I own (Lotsss) except the Lovehoney Deluxe Wand. Trust me, this seemed unbelieveable to me. If you read my blog review I start out by saying that I always went by the mantra "I don;t like bullet vibes" Then I found the Tango and it literally my go-to vibrator now, pushing aside lots of older favourites such as the iroha, the Gigi etc.
It isnt just the depth, it comes with 4 different constant speeds, compared to the usual 3 that other bullets have and each one ramps up from the one before it (Unlike bullets where you can barely tell a difference) Like Laviela said, it is so powerful and deep that even I sometimes have to turn it down because it is too much (That is coming from a woman who always switches to the top speeds on vibrators and still often wants more) It can sometimes be too much.
I wish I could tell you how it compared to the Mia, but all I can tell you is that it knocks 99% of other vibs, even ones MUCH bigger, out the water. (In my opinion)