I would personally not invest in something like this, because I find services like this to have the exact opposite effect of what they're intended for.
I see no reason why women wan't just use regular taxi's, sure sometimes you'll have unprofessional, bad taxi drivers, but I don't think that happens all too often.
Initiatives like this create unnecessary divide between men and women, all for something that isn't a widespread issue.
In fact, it is a great gesture in the direction of women empowerment.
You call that empowerment? Very empowering, to be too scared to take a freaking taxi...