I believe some of the negative comments made about group buys are a little on the fearful side.
Group buys can work in a developer's favour as they draw in new customers that otherwise would not have made a purchasing decision at that time. As has been stated before, the upgrade path is a great potential for further benefits to the developer. Once people use these tools they may be convinced to stay with the company if the tools are of high quality (which I'm sure would also work in VSL's favour).
Group buys do not take away future potential buyers. People aren't going to think "well there was a group buy recently so I can't buy this product now". Provided the group buys for a given product don't happen too frequently no one that is ready to invest in a library is going to hold off for a year or so in anticipation of a group buy.
Developers benefit, customers benefit (old and new, as the company becomes stronger through a greater user base), and we see growth for future developments. In my opinion a win/win situation for all.
It can be dangerous to sit at the top (quality wise) and ignore what's happening below (avid and digidesign come to mind). While I do think most VSL products are good value, for the professional and considering what you get, I also think you have to remain competitive. I hope VSL isn't taking the elitist approach.
Tom