There are a couple reasons why there have been no comparisons. First using a Starter Kit is like your first sex. You are only a virgin once. So its hard to compare first sex experiences - nobody has had two.
For example all Starter Kits (I presume) show you how to use themes or the role and membership features that are new to 2.0. When you first encounter new features they can seem a little odd or obscure. However after you are acquainted with them for a while they seem "natural" and easy. This is, after all, one reason why you use a Starter Kit. So if you originally used kit #1 you might have struggled a bit. When you tried kit #2 everything seemed obvious. Maybe life would have been simpler if you tried #2 before #1 - who can say?
There are a couple other reasons for using a particular Starter Kit rather than another. For example there's the desire to build an actual web site. In that case if you were going to try to build an eCommerce site you would be wise to choose the eCommerce Starter Kit - or The Beer House Starter Kit. Of course if you only wanted an eCommerce solution you could just buy AspDotNetStoreFront which supports ASP.NET 2.0. Presumably the commercial product will be more full featured and sophisticated than any free Starter Kit solution. So using a eCommerce focused Starter Kit solution only makes sense if you want to understand .NET 2.0 first and want to use an application (eCommerce) as an learning aid.
A great advantage of The Beer House as a learning aid is the associated book. TBH code is not modular as some have said. It is important for real world sites to disable certain features and this is a little tricky in TBH. TBH house has a Data Access Layer, a Business Logic Layer, stored procedures, and code behind. It can be tricky to trace some of the interconnections. Certainly it would be easier to customize if there were a control panel with check boxes that hid all the details. But would you actually learn much in that case?