I've been slow leveling a Time/Rad Defender and it's been a blast. It very much feels like a "Scrappy" Defender that jumps right in there with Tanks. Rad Blast takes some -res procs, which helps with damage, and Time is a nice mix of tools. Not sure how it'll hold up to endgame/hard mode content yet, but it's been great leveling so far. Just a bit End heavy.