My original Actionbent underseat steering had bar end shifters.  Because they stuck up straight into the air, sweat from your hands would run down into them and corrode them in a hurry.  And the only 9 speed bar ends were Shimano Dura Ace, $95 a pop.  I don't know how the Tour Trike is set up, but something to consider.  I like the grip shift on my Corsa, but didn't think I would before I bought it.  My only negative experience is that once your hands get wet/sweaty, without gloves you may find it difficult to grip hard enough to twist.