Hello, Dr. Scott. Indeed, Apple's iCloud syncing is the only way to sync to Safari on iOS. And BookMacster can sync in
tandem with iCloud as it does with Dropbox. Depending on how you use your browsers and devices, it may be better to use iCloud for syncing between your Macs too, instead of Dropbox. A couple examples, and a list of considerations are given in
this Help Book page.
When you switch on iCloud syncing, the only alternative Apple gives you is to
Merge the bookmarks on all of your devices. So, if you have mostly junk bookmarks and bookmarks which are already on your Mac on your iOS device, you might want to delete all of them first. If, on the other hand, you merge in a lot of bookmarks from iOS, first Pause syncing in BookMacster first, otherwise the
Safe Sync Limit will probably trip.
When you switch on iCloud, wait a half hour or more, with devices on, for everything to stabilize.
To "switch off" syncing via Dropbox, move your .bkmslf file out of your Dropbox folder.
If you're not sure what to do, send me an email describing what browsers you use, what devices, and how often and I'll recommend something.