I never tired Dropbox but I had nothing but problems with iCloud KM syncing. It seems like iCloud worked great for a long time and then I started noticing macro changes were being rolled back and I had missing macros. Since I mostly create macros on my primary Mac I started using one-way sync and have not and a problem since. Minor hassle. If I do make a macro change, I now manually export the macro to a iCloud folder then when I'm back at the primary machine I import the macro there. The macro that I used is in this thread.