dunno, I actually prefer sirloin, for cooking as a chargrill anyway, i like the fat on it...I'm a sucker for fat. On meat anyway. I'd only use fillet for carpaccio or tartare, not enough texture or fat IMO to serve as a steak.
Slow cooked sirloin????? You're havin a laugh.
Shin for stews and pies and puddings. Or oxtail.
Oh yeah, and me missis did a FUCKING GREAT job with the Bleh! sirloins, really cooked them almost perfectly.