First of all, congratulations and keep moving with your album. That's a great goal and I hope it's awesome.
Did you have version 4 previously? Perhaps your lifelong project and having the tools you are used to using work is worth more than having the latest update of a DAW. Sometimes 3rd party compatibility stuff takes a few months to get ironed out when a big new version is released.
I've found the newest tools to be not as valuable as the music I make, so when it comes down to the two of them, I lean to keeping the music going.