Wait, he was giving you a hard time because you, as a sorc, couldn't 1v1 him? There's no reason for a merc to ever lose to a sorc in 1v1. IO does(did..) have some pretty good burst for a sustained class, just the heat management sucks compared to Arsenal, where you rarely if ever have to use your basic attack nor vent heat and thermal sensor override.
Also I'm positive either DPS spec of Mercs in 5.3 will still be able to 1v1 dps sorcs without much issue.