I know this post is a little stale, but if you're still interested...
Yes, it absolutely changed my life. I highly recommend it, even if you never intend to teach.
I think the biggest thing in picking a program is the style of yoga the program teaches, and whether you enjoy the teachers. You don't want to sign up for a certain style and then find out you don't enjoy it, and the same goes for teachers. I wanted to teach Ashtanga and Vinyasa Flow (the styles I practice), but I chose a training program that incorporated many styles and many teachers and I feel I was much better off for doing it. I have gained a lot of appreciation for certain other styles, and found out which styles I don't enjoy. I was able to do mentorships in my styles with my favorite teachers so I still really got a lot of work in that area, but there are things that I did not learn as in depth because I didn't spend my entire program focused on a certain style.
As far as how long of a program you should choose, I think that depends in part on how advanced you are already as a yogi. If you have a good comprehension of yogic philosophy and a strong and consistent practice, including a home practice, and you have the ability to take a month away from other responsibilities, a shorter program may be a good option for you. If you only practice guided (never on your own), don't have an advanced practice and/or don't know much about the non-physical side of yoga, or if you only have so much time in a week that you can dedicate to your training, go with a longer program. A longer program will give you a chance to digest everything you're learning, while a shorter program has the benefit total immersion. Either way can be life-changing.
As far as YA, I did a YA program from a studio that pretty much hated YA. The YA requirements are a base - a good school will use them wisely and you will get a lot out of the program, but a YA-approved program is not automatically a good program. Similarly, there are many non-YA programs out there that are excellent. If you're thinking you want to teach, go with a YA program as it can be easier to get your first job with the registration and the letters after your name. Many gyms require some sort of certification and they don't really see a difference btw. registration and certification, and YA is nationally recognized.
Feel free to PM me if you have specific questions or want to chat more.
OMG I just noticed you're in Minneapolis. Which programs are you looking at?