I fly a couple times a month with my gear and it's always different. I try to ship it if possible. I checked all my gear in once with Southwest and was called back through security because the case was over 100 pounds. I had to bring a couple of batteries back through security and of course that led to a full cavity check. I keep my big case to under 100 lbs no matter what. I've been Fed-Exing the gear lately. Production seems to like that better and they don't blink at the price. Fed-Ex will also react differently to the same shipment. I shipped my cart last time and had no problem out of LA, but they wouldn't ship it back out of Baltimore! They had to ship the cart freight, and then the guy that delivered it was supprised that they took it. All I can say is call ahead, no matter how you are getting your gear there. Write down the info with the person's name (preferably a manager) and the rule number. Every airline I've gone through has had different rates, rules, and each person you deal with either dosen't know or has a different set of rules.
Good Luck
Dan