Yeah, functionally it's the same. However I think it is a big perceptual change to be in line with the FUTO principle of "we want to make good software that is open and accessible, but we would also like you to pay us for it so we can continue this project sustainably." That's a bit of a contrast with the general open source approach of "I'm writing this software as a service to others, make a donation if you'd like to support my work."
Personally I think the move towards a more structured buy it if you can mindset is great. I've seen too many projects get abandoned because of lack of time and resources and then shift from developer to developer, sometimes getting better, sometimes worse.
I haven't made that same transition myself, but I have moved calendars around with .ics files and it went super smoothly. All events get moved, past and future.