Was wanting to upgrade my chainset to a 48t big one, but all the ones I've seen are being marketed as 9 spd ones, planning on keeping my 7sp cartridge and shifter set up due to cost issues.
You can run an 8 spd chain on 9spd chainrings. Chain rub on adjacent larger chainring may be an issue in more combinations than normal so it's more important to get chain line right. Shifting will be slightly compromised but not likely you'd notice it much.
