I would say that unless your examiners have a good solid 5 years under their belt they shouldn't do them.  I know some of your examiners down here my way and I would never let them touch one,  Residential, yeah, ok. And I am not saying that to be rude or anything by any means.  Just that they haven't been doing searches long enough and still aren't totally familiar with everything.  They ask some scary questions sometimes.  Chris could do commercial with no problems.

There is alot involved and alot that can be missed when you have to run the indexes on companies.  And the liability is much greater.  Though you e&o limits are probably only one million, the value of the properties are often way more than that.  Missing one thing can really hurt the business bad.
If you really want to pursue commercial work, start out slow, in one area where you have a very experienced examiner and see how it goes.  Sometimes the examiner doesn't want to do them because they are so time consuming.  Be prepared to have a second abstractor in the same location for back up so the work doesn't get behind.  And bill hourly.