Yeah, I noticed there's a bit of wiggle room when you look at the length: the Rallybird 92 in the 170 length is listed with a waist of 94. Selling the 99 to help buy something a little slender might be the ticket for me. Of course if I could bring more than one pair of skis on my trips, it'd be a different conversation, but I have to be realistic in terms of likely use.I ski it in that length and am just fine on it.
I agree with @Lauren that the QST was a little more flappable than the Rallybird.
Keep in mind that the Rallybird and Sender have same construction, so if you find the right size in one over the other don't hesitate.
Another side note, When the Sender is listed in one length and the Rallybird is a different length (usually within a cm or two) they are actually the same length. Rossignol has a strategy of trying to differentiate the gender specific skis with different lengths even though they're the same.
If I was casting a wider net in terms of brands, what other 93-94 skis should I look at now that you have a pretty good idea of what I'm looking for (something nimble for moguls but that won't flap around on groomers)?