i have my speakers slightly angled in, but not directly at the main LP. this is because i often am not sitting at the main LP, or i have multiple people listening at the same time. by having them more straight ahead than toed in, it seems to open up the area where the sound quality is at its best. you sacrifice the main LP quality ever so slightly, but i think it's worth it.
as for the sand, the comment curtis made about moving them is exactly why i haven't filled my stands yet once i finish school and have a more permanent spot for them, i probably will fill them. they're quite sturdy on their own, though.
CMT-340SE2 Mains & Center, CBM-170SE Surrounds, Rythmik F15, Emotiva XMC-1, Emotiva XPA-5