I bought a pair of Mizuno Wave Universe 4 in December last year since I loved its predecessor so much. Wave Universe 3 is great shoes. They are amazingly light and provides just enough support for me to run fast and not get injured at the same time. I knew about the upgrade earlier last year, but knowing WU4s are basically the same shoes with no significant upgrade, I decided to wait a little, especially MSRP was $120 then. However, as soon as I saw a price reduction ($89.97 on Amazon.com), I placed an order. Now, you can find them less expensive at Amazon, Running Warehouse, or other online retailers.
As I mentioned earlier, there are not many differences between WU3 and WU4. Technical spec on the manufacturer’s web site shows few differences. Their appearances are identical except for the color scheme and design/pattern. WU4 might be a bit heavier (3.9oz for WU4 vs. 3.8oz for WU3 in size 9). Heel to toe differential is the same at 5mm. They are both width size D, which is perfect for my feet. The toe pocket provides perfect room for my toes to fit comfortably in both shoes. I hear insole is different, but this is a moot point for me since I wear socks with these shoes.
So far, I’ve run over 80 miles on WU4 and 130 miles on WU3. Despite the light weight, sole and cushioning materials seem to have weathered the pounding very well from running mostly on asphalt and concrete. I ran Rock ‘n’ Roll Half Marathon in WU3 comfortably, and since January this year, most of my running has been in WU4, except for 20 miler long runs (worn Kinvara 2). I am still debating whether WUs are good shoes to run a marathon for me. I plan to run Boston in Kinvara 2 but keep training in WUs and perhaps run a marathon in them later this year to see if they replace Kinvara 2 in marathon, too. I will share the experience here.