There is no real change in Keyboard Maestro's position.
Keyboard Maestro can handle text expansions, and hundreds is no real problem (thousands would be a push, and many thousands would be a bad idea). The only real limitation with having large numbers of text expansion macros is the cost in terms of the macro file size. Since the macro file is read and written as a single complete file every time you make a change to your macros, if it gets significantly large that can cause a performance problem with the editor. That said, if you have a SSD, that would make those file writes much faster and might well significantly reduce the issue.
Each simple typed string macro occupies about 200 bytes, so 600 expansion macros would be around 120K, and my own make file is around 1Meg, so I doubt that would cause any problems. Even 6000 probably wouldn't be too bad - but I have a fast Mac with a fusion drive. A very slow Mac or a vert slow harddisk might make for more problems.
I did have one customer who has 300MB macro files (not because of expansions, he stored lots of images in the macros) and he had performance issues in the editor which did not surprise me.