Like everything else ... it depends
- why you want the type
- how price sensitive you are
- how worried you are about the SWA training
- what your timetable is
If you want the type to interview with SWA then it doesn't matter what model of 737 you get your type in (it doesn't effect hiring)
Being trained by someone who KNOWS SWA and will put you on the right track is nice. I've heard Higher Power will do this, but I consider this a luxury, if you can save big bucks and still meet FAA standards at the end then go for it. The important thing is getting the training and the piece of paper to prove it. If you learn the SWA flows then your time in Dallas will be easier - but it is not going to effect weather you get the job.
IMHO getting it in the two is fine - SWA will train you to thier standards when you get there, and the -200 is simular enough to get you the right idea. In fact I think you're better off in a -200 then in an EFIS bird, because we fly round dial.