Ascorbic acid is the preferred form of vitamin C to take if you want to minimize gastroentestinal problems. But there will always be the problem of bowel tolerance when using oral forms that don't use the liposomal process. Oral administration of plain vitamin C, even of very large doses, can raise plasma vitamin C concentrations to a maximum of only 220 micromol/L. Whereas IV administration can produce plasma concentrations as high as 26,000 micromol/L. Liposomal vitamin C has been shown to consistently achieve plasma concentrations on par with intravenous vitamin C, and sometimes surpass it.

As I said, oral use of plain vitamin C has its place in a daily maintenance regimen. However, if I were getting sick I would turn to the liposomal form.