What feedback is given other players when I insta-res them with the Siren's Phaselock?
I always play Borderlands 2 co-op, never solo, which means that I'm always with friends. They like to play damage and I like to play medic, so we work together well.
I have my Siren built for healing first and damage second, and the most useful ability in my arsenal is the insta-res 'assistance from a distance' ranged heal.
I'm selfish, though, and I don't just want my buddies healed, I want them to know who healed them. I want them to be so grateful to me that when the time comes, they can't shovel the good loot drops my way fast enough.
What feedback, if any, are other players given when I insta-res them with the Siren's Phaselock?
They stop being dead, which is a big one. If there's only one Siren on a team it's incredibly obvious when a Siren's res'd you (after the first time, which is a bit of a WTF moment). The only way to insta-revive without a kill (which is denoted, separately, when it happens) is a Siren's res, so it's pretty apparent when you've been healed by a Siren as opposed to the slow, manual heal.
Aside from that, you get the standard "X used res on you" message, similar to the "Kill revive!" message you receive when you're using the manual revive and someone gets a second wind on their own. If they're paying even the tiniest bit of attention they'll notice.
Firstly, BAD HEALER! Healing is about making everyone else more awesome, not about glory.
Secondly, while I am not at a computer with BL2 right now, so I can't provide a screenshot, yes, it does pop up with a message of " used Res on you!", or something to that effect.