Just an obvservation from someone who is new to Sencha: I think it's a bad business practice to hold back bug fixes from the "free" version of the software if you are going to offer a free version to begin with. Whether you're alone in doing this or not, it doesn't really matter - I just think it's a bad idea.
Reason being, I am developing a prototype for an app right now, and how the development cycle goes and how the software performs is what's going to decide whether we use it for future development. Right now, the way it looks to my boss is that 1) the product is buggy, and 2) no one will respond to questions about it.
We have absolutely no problem with purchasing support and consider the benefits of the premium plan (performance tweaking, code review and other perks) to be well worth it - IF we have faith in the product and the support staff to begin with. Holding back bug fixes from the free version in order to get more paying customers is not a very good PR move! If you can see it from our perspective for a moment.
I really like the product in general, and maybe my introduction to it has simply come at a bad time, but I'm probably not the only one who feels this way, and a lot of potential customers have probably walked away from it altogether out of frustration, rather than take the risk of seeing what happens when they buy support.