I know this answer!! I was just talking with a HQ rep actually and it is very doable - you do have to get the tracks for the machine/frame.
I'm getting the HQ Sweet 16. I opted to not get the Tiara because my local dealer would only do MSRP and I would rather get the original for a better price
I will say that I regret not buying it at the quilt show I was at a few weeks ago because I would have gotten free shipping which would have saved me $190. I really really regret it but I wasn't 100% sure until I test drove the Tin Lizzie sit down (which is NOT convertible to a frame btw) I decided today to get the HQS16. I'd already have it ordered and ready to ship but there's a show 4 hours away in 2 weeks and I'm in contact with that HQ rep to see what kind of a deal she'll be offering.... I'm hoping to hear back from her in the next day or two so that I can seal my deal and get my machine purchase settled...