theWILFRED said..
Since you already have a switchblade, i would say stick with the same kite possibly a 7m. this beats having to get used to a different system, bar pressure, etc. SB's have a great wind range so this should cover you for above 30knots.
My first setup was 11/7 and I found I never got out on the 7 until I got a lot better, and now it's pretty much my go-to kite, hence suggesting an 8 over a 7. In truth it probably won't make a huge difference as a beginner and for your first few years.