Yes, that I/OS lens is going to be smaller. I think I had originally found a bunch of different lenses for the I/O at the best price on ebay a while back, but I'm not sure what they have anymore.
Also, just so you know, I've been using the ignitor lens without any problem thus far, but, I wouldn't really say that my eyes are sensitive either. If you do decide to get a new lens though, let me know how it works out for you. Best of luck.