I have C3 installed on a PC along with C4, but I’ve not used C3 in years. I tried to start C3 out of curiosity and had to update the license (no problem), but then C4 would not run without a license change (no problem swapping licenses). With that said, C3 and C4 would run but my machine required differences licenses. I cannot answer, “Why?” I do remember swapping from C3 to C4 and not having any problems sharing a license at one point. I do not remember any issues migrating to C4 from C3. From Cantabile download page:
My suggestion is to backup your computer and see what happens. You should be able to have C3/4 running on the same machine, but backup for safety. C4 does not overwrite C3 (they are both on my machine and run if the licenses are viable).
Migration is a piece of cake. Just make a backup of you personal files (song, rack, etc), and install C4.
When you install v4, a “copy of everything-you-have” will be created from v3.
As a general suggestion, do not save a file (song, rack…) from v4 to use later on v3. This is because of features that may not exist on v3.
This is even more true if you planned to use the 41XX version.
Not really. At least, I had (and still have) full compatibility. Someone reported v4 is a bit more CPU hog. I didn’t see differences, but I have pretty simple songs.
Sure. A little hint: Be careful which icon you use to start Cantabile. In my PC (who knows why), I experienced issues because both 32 and 64bit Cantabile were installed, but I can’t say what went wrong that time.
I fixed that by deleting every icon running the 32bit version.