It very very much depends on procedures. With the standards of the EU, a mixed mode operation will give you a higher throughput than a segraded mode on a single runway. However, it depends a whole lot of fleet mix. The more Heavies you get, the more you gain with mixed mode. If you're all Mediums (i.e. can come in with 2.5nm seperation and leave with about a 6.000ft speration) it doesn't really matter much. But in DEN
the taxi from the terminal to the 26 is lengthy. Another thing you never should forget is airspace. Even if you have a fleet mix and conditions that allow you to spit out 60 or planes off a single runway doesn't mean the airspace can cope with it. Famous example are for example 22L departures in ORD
in 13C mode give trouble, other problems can be found with JFK
interaction. Also en-route airspace is a problem. I've already been sitting in perfectly good WX
at a smoothly running MUC
airport for 45 minutes to get an en-route slot to LGW
because airspace over western Europe was crowded. RVSM have allevated that problem a little.
If I look at my home airport, MUC
it does operate two runway in mixed mode, yielding 90 operations an hour (maximum landings and take-offs at 58/hour) in IFR conditions with non-contaminated runways (i.e. dry or wet). Perfect VFR mode give over 100 (107 was the max afaik), fleet mix is around 7% Heavies plus a bunch of 757s.