"The national trend is for states to reduce corporate taxes to attract and keep businesses." 

A race to the bottom. From what I've read local taxes have little to do with why companies move to a state. The quality of the educational system is a more important factor, and taxes support that. As the Oregon Center for Public Policy has pointed out, Oregon corporate taxes have been going down for a long time. We've been giving away the state.

http://www.ocpp.org/2016/06/29/nr20160629-corporate-tax-decline-dramatic-oregon/

"Measure 97 is going to make the poor thru the lower middle classes pay even more than their current share of the tax burden." 

I don't think so. You're assuming that these large, mostly national corporations will change their prices just for Oregon. I doubt it. They're also limited by competition and what people are willing to pay. When they raise their prices I cut back on what I buy.