Jesse,

If there were a limited number of holes to drill, a steel fabrication
shop would probably use a magnetic drill and annular cutters such as
rotabroach. You don't state the length of the beam but if you can get
it on a mill table you could use the annular cutters in the mill.
These cutters are not cheap but they are a big step up in performance
above a hole saw. You cannot use these cutters in a portable drill
because the setup needs to be fairly rigid. Here is a link to Hougan,
probably the most well known manufacturer of annular cutters:
http://www.hougen.com/cutters/cutters_index.html.

Depending on the accuracy of hole required a second alternative would
be to plasma or flame cut the holes using magnetic drive circular
pattern cutter. You would need to go to a welding shop to have this
done. Depending on the number of holes, this alternative would
probably be cheaper than buying cutters.

IMO the Travers circle cutter that you are considering is not rigid
enough to cut through thick steel. I have used such a cutter in wood
and it is barely rigid enough for that application. I consider them
somewhat dangerous. Also it would be even slower than a hole saw.

Ron