If you're asking if they can be connected together between models, short answer is "yes," SLE's all have the same ferrule size except when you get up into the PB 2-4 and 4-8.
Only differences would be the overall lengths of the SLE sections. Anyone know offhand the total length on the 1.5?
I know what a SS uses but not a 1.5, I imagine the 1.5 may be slightly longer. Center sections may be the same but I can't confirm.
I see 92" on a few sites for the 1.5 SLE, my SS was 90" overall, so you'd most likely have an extra 1" on each side. You'd have to cut the 1.5 SLE ends most likely for them to fit OK, or perhaps put longer bungee's on the SS if you don't want to do any cutting.
Just don't break anything.