I'm pretty new, and have only made 5 kits in the past 3 months, but I started with two 10's (WE's Trinity White and Red) and now have done 2 16's (one with skins) and an 8??
I did a WE LE pinot and the WE VR sangiovese (8??) at the same time, and the 16 L had WAY more solids in the bottom of the fermenter. I posted up a link to an article in a different thread on winemaker mag where Tim Vandergrift talks about how the more concentrated the kit, the faster it will become drinkable. That is the reason I'm going to do some smaller volume kits, so I've got some mature wine to drink earlier than in 24 months.
To codeman's point, most of the 23 liter kits get diluted, just moreso with the smaller, more concentrated kits. I don't have any experience with the VN kits, so don't know if they are 23 at volume or not.
If you want that cab - franc mix, I'd say get it and go. You might need/want to spice it up a bit with some tanin or oak in the bulk storage to give it a bit more "oomph", but I'm sure you will end up with a nice wine.
Best, Fran