The only reasonable concern regarding electronic voting I have seen addresses hacking; however, that fear is much over hyped. As an election judge that has used both punch card and electronic systems (e-slate in Texas), I can tell you that hacking of any electronic system requires fraud/insider dealing at the very top of the state electoral process. If that occurs, the system of voting doesn't matter.
The computer should handle ALL counting. No bias in the computer. Two more things. 1) A Republican in Every Precinct serving as judge/clerk/poll watcher and 2)REQUIRE IDENTIFICATION AT THE POLLING STATION.
I really don't trust the other side. Hundreds of millions are spent electing a President - the whole world's a stakeholder.