<p>I have several long running report type transactions that take 5-10 minutes. Would I see any performance increase by using stored procs? Would it be significant?</p>

<p>each query runs once a night.</p>

yes, the query plan for stored procs can be optimized
and even if it can't procs are preferred over embedded sql
"would you see any performance improvement" - the only way to know for certain is to try it
in theory, stored procedures pre-parse the sql and store the query plan instead of figuring out each time, so there should be some speedup just from that, however, i doubt it would be significant in a 5-10 minute process
if the speed is of concern your best bet is to look at the query plan and see if it can be improved with different query structures and/or adding indices et al
if the speed is not of concern, stored procs provide better encapsulation than inline sql