Yes, the migration method would work, but ... much more to do ... and as with anything else, the more to do the greater the chance of a 'hickup' or a 'brain cramp'. Let's say you did that ... ok you've worked on the online version for a month or two now and decide it's 'faster' to work locally. Download code happens once, but you need the data directory and an SQL dump of the online server (both of which have grown) to restore to your local. Then after making changes/adding to course content, etc., one has to do the reverse ... data directory/sql dump ... shouldn't attempt overwriting (that could bite ya).
Anyway back and forth for a while and then one day you forget which is the latest and greatest creation and guess wrong (braincramp) and restored your local version (that hadn't been collecting grades nor has any student work in it) to the online version ... uploading and restoring an SQL dump *without* the data directory that goes with it can wreck a site ... maybe permanently.
Uhhhh ... hate to say it, but been there done that kinda thing. Not fun! Have oft told folks I'm no better a techie than most ... but have learned (the hard way) what doesn't work!
We all, however, have the choice to pick our own methods of madness.
'spirit of sharing', Ken