Yes, that's clear, however the page builder itself is much more important for me and I found the SP PB is the better and more handy than T4 builder.
So I choose it.
What about the framework, it's not very important which one to use, but in helix I feel lack of that fancy possibility to include joomla modules into layout intead of placing the positions.
By the way typography and color management I like more into the T4 framework as well.
Finally if htere are some possibility to edit header, footer and visual edit css of site into the page builder, I don't need the framework at all.
PS: builder works well with the rest frameworks like astroid, etc..