morning all..
Easy answer. They last a long time...
EVOD's in my opinion perform about the same as a MPT (mini protank). I believe the heads are slightly different, but are never the less interchangeable, so it's perfect for you. If you like your MPT and feel you need a backup at a budget then an EVOD is the way to go. Both tanks are very durable, only 2 main differences are; one looks great and one looks bloody marvelous. One is plastic and the other is glass. Mostly it's a look thing but some liquids have been known to haze or crack plastic tanks i.e lemons, grapefruit, cinnamons.. etc, but don't let this confuse you further, you'll work it out.
I am a big fan of EVOD's - High performance low cost and maintenance and at that price you can't go wrong.
BTW. I noticed from the link you gave that your MPT kit came with 5x 2.5Ohm heads and an EVOD battery? If you have the chance to pick up some single heads on your next order, try a 2.2Ohm and maybe a 1.8Ohm replacement head. You might find you get better results on your 3.7v battery.
Good luck