In my humble opinion STAY IN FOR 6 more!!!
Get as much pension and goverment benifits as you can before you eject!
If you want to work for a Low Cost Carrier, they are just now starting to run into their finacial snags, but if that is your goal then SWA is the best in the Low Cost Carrier business. However I will see those guys running into their snag in the not so distant future as well. The MAJOR airlines have tons of guys on furlough now, and it will take a while to get them back on the property. I also fully expect some of them not to come back at all since this business has gone down the toilet and they have since started in other careers endeavours. I can't speak for the cargo side of the deal since I am not one into flying the night shift, then going home and spending my days off trying to stay awake during the day. Not my cup of tea. I am also not that familiar with how they are doing.
All I can say in the nicest way possible is you would be stupid to bail now. Stay in there for 6 more specially since you do like it anyway.