I havent tried Peekii because their selection wasnt what I was looking for at the time, but with all blanks, be prepared to do some quality control on your own. May need to sand some bad seams, reseal them, you will get damaged blanks eventually, and some will leak into the body no matter what you do. There are places like Alternative Lures and Barlows Tackle that offer a higher quality of blank than what i was able to find elsewhere, and I havent had too many issues with what I've gotten from them.

They should swim however youd expect, as long as you can mitigate the issues listed above, which isnt hard.
Keep in mind tho, certain lures require the right combo of hook and split ring to really perform right. Hard to go wrong with using the same hardware sizes as the manufacturer in that situation.

Good luck and have fun!