I personally love working with beginners. I also love working with people at or above my level. I always seem to learn so much about every aspect of aikido while working with newbies. You end up teaching them (in little snipets) history, technique, ukemi, philosophy, etiquette, etc. But, after I've learned new things about techniques from working with the new folks I need time on the mat with someone at or above my level so I can work all those new things into my aikido. So yes working with beginners is great but I think we all need some time on the mat when we're focusing on training ourselves. I can usually get both of this in the same class. Work with the new guy, discover something cool. Next, work with another yudansha and try to apply cool new discovery, file it for later use.
So after all that rambling (it's 5:00 a.m. here) I guess my advice would be to go if your allowed to. If they didn't want new people there they'd make it a yudansha only class.
Just the half sensical ramblings of a sleep deprived mad man.