I generally don't agree with removing 9th level spells from magic items altogether. I am in favor of putting some kind of restriction on them (like, 'must possess skill to use item that duplicates it', or 'must possess ritual levels in school to use items above (6/7/8/9/?)th level' or something.) I see a great number of casters use rituals like Exp. Enchant, Channel, and Spellstore to enhance their own casting ability. I would like them to be able to keep doing that. I think removing the ability for casters to grant themselves more of their own power is one of the things that makes ritual levels attractive. For every few ritual levels you buy, that's another handful of spells that you could have bought. It would be nice if they were still useful in a 'at least I can still use some of them to get more spells, via exp ench/etc' kind of way, since they're otherwise not used much.
And yeah, we just cast a diff 30, a 31, and a 29 at the last event I was at. (Specifically, Seth (Alavatar) did, just to reflect the weight I consider his opinion on the matter to hold.) (They were a 19 rit Permanence, a Spellstore 13, and a PA 4, for the curious.)
~Matt, WCV