This is a cool patch. It's relatively simple at its core, but it goes a long way towards dispelling much of the dark magic involved in manipulating Mario's graphics routine. Truly a boon for hacks in need of more elaborate custom player characters.
There is, however, one fairly noticeable bug to be aware of - the bottom half of the player sprite on the overworld border briefly draws garbage when the windowing overworld transition is active (i.e. when switching maps via a red path tile). Pipes, stars, save prompts and level fades (to and from) all work fine. It took quite some time to sniff out the issue, but it seems this patch is at odds with some code applied by Lunar Magic upon saving the overworld. Applying this patch before or after saving for the first time makes no difference. I've made the decision to approve this update as version 1.2 seems to suffer from the same issue anyway, but a future update to remedy the problem would be welcome.
Tested with Asar 1.71, Lunar Magic 3.03 and 3.04, SA-1 1.32, Snes9x 1.59.2.