Just two thoughts..I also bought the modular strop..I have not used it as it has not arrived yet but I felt it was a nice complete package so that you have as many bases covered in one shot..

Second you are going with the Norton set up..they have the four grit combo which is more cost effective because you also get the 220 and 1k stones as well with the flattening stone..
Once again looking at price and covering as many bases as needed. A 1k makes bevel setting easier..
Hope it helps and good luck.