Tank supp main here, and I was dreading the loss of FOTM enough that I swapped to mid and top for a little bit so I wouldn't have to deal with what I thought was going to be a pretty awful change. Jumped back into it yesterday and I gotta say, while I still hate not having my shield battery or at LEAST my FOTM active, it's not even close to awful.
500g on a targons I would have bought in the first place and now I'm saving 800g on a sightstone, lets me get wards up a hell of a lot earlier so I can start making plays a hell of a lot earlier. I lose valuable tankiness but I gain vision and now I can rush literally anything else - KV, glory, locket, whatever, and this actually makes up for some of the loss of pure shield/hp.
It's not fantastic but it feels good to play. More streamlined and honestly it works out really well. Even if it's not my favorite I'm actually happy with the change.