Just adding my two cents to the topic now that I've tried them.
I've recently installed the Uni foam filters. I came from the K&N Pods.
I've had some good trips on the bike now with both the K&N's and the UNI's, and I can't say I see a huge improvement from the UNI's. I started by cleaning my K&N's, running the bike for a couple local rides, and it ran beautifully. I changed the K&N's to the UNI's and have run the bike on some good long rides again. I've noticed only a slight improvement over the K&N's in the area of smoother throttle response while cruising at a steady MPH with only moderate throttle fluctuation in 3rd, 4th, or 5th. When you get on the throttle I think the carbs are just pulling so much, that you wouldn't notice any difference between the two. However it is a nice improvement while cruising.
I've noticed that most of the people I ride with and the bikes I see pictured here have dirty sometimes filthy air filters. And, I think what people are noticing most when switching is a CLEAN set of filters...
I've always been really on top of cleaning my filters, I live in a dusty county area. Cleaning the filters often, has always been necessary. And the change from filthy filters to clean, is ass puckering... I like the look of the K&N's more than I like the look of the UNI's. So when I feel I need to put the K&N's on with the chrome ends, I'll do it but make sure that they are nice and clean. But because of the slight gain of smoothness while cruising. I'll keep the UNI's for most of my riding.
If you have pleated pods and you're on a budget, just make sure you're keeping them clean is all. I don't think the purchase is necessary. However if you don't have filters yet for your bike. And, you have to choose between the two. The UNI's do make a bit of an improvement and cost less than the K&N's.
Hopes this helps.