Ken -

You must really love your Sigma 150/f: 2.8 macro; it (along with your E-1) certainly does perform in your hands. The lens looks to deliver plenty of resolution and contrast.

You mention using 'external' flash set-up. One of these days you might consider sharing your technique ;-)))

-leon

Well I feel for macro you have to get the flash off the camera. Myself I use a Manfrotto flash bracket with extensions, and an Oly flash cord, diffused with with a painted Gary Fong Lightsphear. No matter how you do it, the flash should be diffused, which will require exposure and flash compensation.
As an example here, (this is not me), this guy uses a coke can with paper towels...
http://www.fredmiranda.com/forum/topic/560078
And he extremely successful at it.

Good Shooting...