I really liked reading this. Giving relevant names/titles to pricing tier can be very effective. I immediately understood the diff. b/w freelancer vs studio instead of saying Basic vs Premium.
You might find that further tweaks push more people to the agency tier by creating a "slightly ugly" agency instead of a "slightly ugly" studio -- freelancer.
http://www.ted.com/talks/dan_ariely_asks_are_we_in_control_o...
The people who buy it come from different backgrounds and I don't want to segment the product.
It's a recipe plugin and the premium version adds a nutrition tab to satisfy the nutritionists and category listing pages for people who want to organise their recipes more than what the free version allows.
Any thoughts on a name?