No, I'm pretty sure Ben Browder was the original lead for Farscape. Certainly his character was -- the whole show was about an Earth guy stuck in a completely alien situation -- and I don't think any other actor was playing it.

PJ

"You told me you weren't like other men," she said, shaking her head at him when the storm of laughter had passed.
He grinned at her - a goofy, Clark Kent kind of a grin. "I have a gift for understatement."
"You can say that again," she told him.
"I have a...."
"Oh, shut up."

--Stardust, Caroline K