I have very few of these: an electric/electric blaster, an ice/ice tanker, a ninja blade/ninjitsu stalker.
Of these, the ninja is probably my favorite, since I do NOT dote on all things Japanese, and the character's concept (La Faiseuse d'Anges) is about as far removed from Japan as it is possible to be.
I used to play the blaster a lot more, basically a blastfender concept, until changes to the /electric secondary sent her into semi-retirement.
The ice tanker has the tissues that come with Ice armor. Built as a melee controller, she is certainly playable but is slow DPS even for a tanker, and was made in fulfilment of my vow of having every armor set (except Stone) and every melee attack set (except Super Strength, which I will not play in its current form) at 50.
Count me in the faction that would take Invuln/SS as a matched pair. There are a whole lot of matched sets among the melee sets (Fire/Fire. Dark/Dark, Stone/Stone) that would seem to me to not have all that much synergy, and where the sets would benefit from a mixed up pairing.