Thanks for the info, Mark. Based on your excellent breakdown, I think we'll try the SMS route first. Reason being we use messaging infrequently and that Verichat when open seems to access data more often which affects my ability to get phone calls and also the battery life.
It is an excellent application and for me, if I had more IM buddies I'd be all over it. For now, I tend to call them if we both can talk at the same time and I was just looking for something to send messages to my husband.
I'll keep playing to see if my usage model with change.