So I've found that the Text( command spaces are excellent for erasing sprites, but on some people's calculators it seems to erase one pixel below the space as well.

The TI-Basic Developer wiki says this:

"On the TI-84+ and TI-84+ SE, the Text( command may also erase a single row of pixels underneath the text: whether this occurs or not depends on whether it was the menu screen or the table that was visited last, of the two."

This is very vague to me, and I don't understand what "the menu" refers to, since it clearly isn't the homescreen. Anyone have insight?

It means the Mode menu, if a calculator visits the mode menu, a flag is set that makes text erase the pixels beneath it.  Visiting a menu such as the table selection, or the metrix editor resets the flag.  On the newest OS however, there is no way to reset the flag, which can be annoying to games that rely on the text not having the erasing underneath.

Yeah I hate that XP

Grrr... Can someone think of a different or better way to erase 6x6 sprites? I used to do it with lines before I though of the Text( way, but the speed benefits are such that I would find it hard to return.

Courtesy of ztrumpet in his Vertical Text Sprites topic:

Edit:  After I wrote this, TI released OS 2.53 MP.  It messes with the flag so you can't reset it with G-T.  Instead, you must use a small Asm program with this hex code: FDCB058EC9  However, on the old (read: better) OSes you can use G-T.

you're correct, but it's one of the way XP
Probably using that hexcode will help you a bunch though.

If you use Pt-Off(X,Y,3) you might be able to turn it off pretty quickly using only a few hardcoded commands

Oh whoops yeah i meant Pt-Off(X,Y,2) I forgot which number was which   And there is no direct way to read the flag, but you can test it by simply displaying a pixel, and then display a space above it, then detect if the pixel was erased or not

Use pixel-test() to determine the color of the pixel