I've tried it a lot of places, and it's never been satisfying anywhere but in the jungle. If you go 9/9/12, you get most of the early offensive and defensive stats you might be used to, and you'll also get Runic Affinity and Alchemist as a bonus. It's mostly useful on heavy farm junglers who want to chill in the jungle for a long time in between recalls. Even then it's not amazing, just viable.
I don't feel like allowing people to get the spellvamp/lifesteal AND offensive masteries at the same time is a good idea, though. Most likely the sustain would either be strong enough to be relevant, in which case you'd HAVE to take it, or it wouldn't be that powerful and would remain uncommon. There are a lot of sustain masteries out there already, though, so I'm not sure that just making it into another sustain mastery would be ideal, either.
At the moment, supports tend to take 17 points into utility without very much variation in what they take high in the tree. The first 8 points in the tree are pretty variable, but in tiers 3, 4, and 5, they'll grab Greed, Culinary Master, Scavenger, Wealth, and Bandit every time. That will leave you with 2 points to allocate somewhere. Ideally, I think it would be nice if supports had a choice Inspiration, Meditation, and Vampirism. If those three were changed to be balanced with each other- and I'm not sure how you'd do that- and each had a cap of 2 points, you'd essentially have to choose between them. Meditation would help you poke more if mana gated you, Vampirism would help you trade more, and Inspiration would help you keep up in levels if you roam more.
Both Vampirism and Inspiration feel pretty weak- but more so Inspiration. As it stands, it would take 5 minutes of standing next to a higher level champion to get from level 1 to level 2. That doesn't sound that bad, but it would take over 30 minutes to level from level 17 to 18 from this mastery. It just doesn't do very much. Even for 2 points, that's not worth it. Not sure how much it would have to be buffed to be valuable, but I'd definitely want it more powerful.