I'm a big fan of both the single and (newer) dual-flange SpinFits. They're both very comfortable. The dual-flange gives better isolation and slightly tames the treble energy. I'd both both - this basically.gives you another tuning option for your FLC8S. They aren't the cheapest tips (dual flange are $10 per pair), but being silicone, they should last.
Which one of them fit better? I slightly prefer dual flange because it's newer, but also concerned about comfort because of it's non traditional design.