Re: the churnable question -
I received the regular card (the $49 fee) in early 2014, and then was considering the Premium card earlier this summer. I asked both VX and Comenity if I would receive the 15K signup bonus on the Premium card if I applied, since I was already a regular cardholder. They both responded with a resounding YES, as it had been over a year since I applied for a card with them, so I applied.
I applied and was approved for a "new card". But then, instead of getting a new card for the Premium, Comenity instead "upgraded" my old card, and charged me a prorated annual fee for the remainder of the year. When I called to ask about the bonus spend, Comenity told me I was not eligible.
So. Wrong information abounds, on both the Comenity and the VX side. I love flying VX, but the awful customer service from both Comenity and VX makes me want to jump ship.