I am not sure specifically about
what you are asking and would like to hear on this myself but I don't believe there is any disadvantage per se because I know there are programs that do dividend reinvestment and that results in
fractional ownership of a share until it becomes a full share and while only your «whole» shares are «traded» when it comes to actual worth, your
fractional count too, so I assume from that if you had «whole» shares no matter
what the amount, you'd be proportionally invested as anyone owning more shares, just to a lesser extent.
While there is much that remains unknowable in financial markets,
what we do know is that Graham's «big idea» — that a common stock represents a
fractional ownership interest in a business and that the essence of investment is to attempt to exploit discrepancies between the intrinsic value of a business and its price in publicly traded markets — has empirically and practically worked over the long term.