Most people just opt for the latter because if you ever send more texts a month than $20 it "pays" off in the end.
Both options suck, the phone companies not being able to gouge for texts is no love lost in my opinion.
How has dropping texting entirely worked out? I've often wondered what the impact would be myself. Not that I have the balls to do it.
Maybe there are costlier satellite data plans. A quick search of Iridium's plans revealed no prices, just resellers and offers of quotes, which indicates it may be really pricey.