Mav is right (there, I said it), you need to do a little basic research on how VIX futures and VIX options work first. There is a very nice primer about VIX futures and options from one of the dealers, I will try to post it here tomorrow.
As long as you can stomach the inconsistencies, no. But just understand that certainty in the VIX space is an illusion. All models are simply a best guess. The instant a dislocation occurs, there's new data to contend with, making the predicted p/l from the moment prior no longer relevant. Risk graphs are not useless, but at best they're simply guides as to what might happen....If I'm using TOS as my broker and their graphs to plot my strategies, as long as I'm making a profit when I should be making a profit (when their version of VIX increases) and losing money when I should be losing money (when their version of VIX goes down), does it matter in the long run who has the 'correct' model, if there really isn't one?
I'm trading VIX calendars on a regular basis, and most of the time, I'm filled 2-3 cents from the mid on the calendar. The interesting thing is that IB allows a penny increment on the spreads but only minimum of 5 cents for the calendar. Which means that you have a good chance to get a better fill on the calendar than on single options, although in some cases I did leg in/out and was able to get filled on the mid on a single options.