I was inclined to rate this slightly higher than Sower as she is more robust due to having persist however most of the time you want to make this guy with a mana open as tapping out to drop a 2/2 you don't want involved in much combat and therefore doesn't offer much tempo can be very risky, it can easily lead to them untapping and getting out the card they were holding back for fear of other counters
Really, my favorite format was fine without it
Greed and Bolas's Citadel are also incredibly strong options for this strategy in commander
While those cards reward you for equipping creatures, this makes the equipment themselves generate additional card advantage
Take my deck, for instance: When we were still forcing Sapling of ColfenorSapling of Colfenor as commander, this card was worth the four mana because I could see that I had a creature on top to draw, or could get a land off the top of my deck so I didn't whiff
There are many new Fractius, such as Lazotep Sliver, Regal Sliver, Taunting Sliver, Hatchery Sliver and many other new cards