Jan, I like Dipped In Dots the best. Some nearly identical irises are really not that identical when you have them planted in your garden and can see the substance of the petals, the beard color and size and the subtle shading and form of the bloom. The ones that are very much alike should be evaluated on how long the blooms last, how hardy they are in your area and how the blooms stand up to the sun and weather.... i think. I am seeing new introductions that are very much alike some that i already grow. There is enough difference to make both desirable and enough space to grow them in different areas...... just not enough budget to justify the purchase.
Poly, I water my irises all summer long. I like the way irises look in all seasons but most people in this area call them 'drought proof' and leave them to their fate. This causes brown tips and often half the leaf will brown off. I don't like that. It makes me think of dying plants. So.... i water at ground level. The very tips will tell me if the water is not reaching the roots.
Our summers are so dry we only have leaf spot in some springs and it does not last long thankfull.
A few of the irises looked relatively clean, most so-so, a few relatively bad. The Good, the Bad, and the Ugly. 
I remember at least one that was really bad last year; I guess I'll be seeing how bad it gets this year.
