I am only 5'2.5" with a 29" inseam and have no standover issues on Specialized's small FSR or HT. I was VERY worried about standover but it is a non-issue for me. After I realized that I could focus more on reach, luckily Specialized uses a more compact cockpit than a lot of manufacturers and so the "unisex" bike fits me like a glove. I still have people tell me us short gals can't ride 29ers because of standover but have you seen Emily Batty? She is tiny!
See if they can get you one to demo, that is the best way to see if you have standover issues. The Tango is an interesting design, I think you will see more and more manufacturers experimenting with shorter standover 29ers. When I bought my Gary Fisher FS 26er back in 2008 there was nothing I could standover in a 29er (Austin was definitely flooded with them to try). Fast forward to 2011 when I got my Epic and I had plenty of options to try.
Amanda
2011 Specialized Epic Comp 29er | Specialized Phenom | "Marie Laveau"
2007 Cannondale Synapse Carbon Road | Selle Italia Lady Gel Flow | "Miranda"
You don't have to be great to get started, but you do have to get started to be great. -Lee J. Colan