I actually performed a test recently using various pens (regular ball point, gel, sharpie brand, Pigma, and an "industrial permenant" marker). I tested with two fabrics ... one pre-treated with InkJet2000 and one untreated - two sheets of each. I test one of each fabrics with heat-setting (with iron) after I wrote, and other without heat setting (4 total pieces of fabric).
The winner was ... Pigma Pens with or without InkJet2000 and with heat setting.
I still have the fabric pieces so I can do a longevity test. Right now they're only a few months old and have only been through 4 washes.