John,
I own both the 1/8 and the 1/4 as there are a lot more bit choices especially as you get bigger like surfacing bits etc that need the 1/4".
As for the one that comes with the Makita it certainly is not bad by any means but I think you get better tolerances with an aftermarket one for sure. Make sure you read the previous thread on this as I got the forum a $5 off shipping discount.
-Alex