What's the advantage of this over storing full public keys at specific intervals?
Also as you target a larger number of keys, your time spent scanning for the bit sequence increases, unless you use some smarter data structures (which would not be as small as 3.81mb anymore)
generating sequences 01001....
The possibility of finding an identical sequence is very low.
The traditional way limits you in space, and it works the same. If you choose 64 as the collision margin you will divide your computing power/64, but with a huge database, you would still find the key faster than using xpoint.