I have a smaller version of the Paragon, the E-10A http://www.paragonweb.com/XPRESS-E-10A.cfm I love it, it holds the temperature very nicely, easy in and out, and Paragon supports their kilns very well. I have another Paragon that I use for lampworking as well, and a huge JenKen that I use for fusing.
I have only used a Vcella once, at a week-long workshop. It did not have a controller, just an infinite switch. The nice thing about it was that it heated up extremely quickly - no hour plus wait to get to temperature, which is nice for enameling or annealing, not such a big deal for fusing. However, on the down side - the door latch was awful, very cumbersome, and you have to really keep an eye on it if you don't have a temperature controller - they will overheat very quickly as well.
Hope this helps, although from the date of this, you've probably already made your choice! :-)
Karin
I have had both the Vcella and an E-10A Multi-media Paragon, and although the Vcella is touted to be the best, I wish I had never given up my Paragon Multimedia - E 10A. It was far more reliable in holding a constant temperature!