Oh, I'll do that. Just after running a Grav/Storm to 50 originally and now recreating her and getting her up to 40, it is going to take some adjustment. Also in some map configurations, you can only back up so far (turns, corners, caves).
Not quite sure on the radius. My typical way to handle a group is to hit them with Crushing Field, drop Freezing Rain, then cycle Gravity Distortion/Lift/Propel (and tornado/lightning storm if I really want some chaos/need to whittle down a boss/EB). In any event I want everyone in front of me, at a comfortable distance. I guess I'll need to play with that distance when I can.
I've never TP'd Singy (or as I've named it, "Big Wisp"), but I do like employing Wormhole to bring mobs to me (mostly to separate groups). I'll probably need to be careful with that now too, to not port them within Singy's gravitational radius.