can you transfer old save files to this version
Yes: I'm using a save from years ago and it's compatible.
Install the new version, load it up, create a new save in slot #1, then copy/paste the old file into it (and rename it "file1.rpgsave"):
However, loaded up an ancient save for the new build and discovered a nasty bug:
If you buy a dog (pet) then level it up, but then do the "hunting the snow deer" quest, it will vanish
permanently if it is in your party when you hit the "cross the frigid stream" part of the goblin quest. Having searched all the spots where it should be left (Giant camp, town, city etc etc), I'm kinda annoyed: grinding out lvl 10 on the dog / familiar is really annoying to do.
The worst part is that if you've saved after starting the quest (sigh) you can't return to the camp to leave it at the spot you're intended to leave it at. -.-
So, yeah, don't do that. Unlike the familiar who actively warps in/out for quests, you need to manually leave the Dog before doing major quests.
~Edit, also the quest "Master's Loot" doesn't complete even if you beat the red-haired vamp & get her to wear it, but that's kinda just minor. But it's a bug that hasn't been fixed since I last played which... was over 3 years ago.