Yes, we did this in 2014 and we had a great time! The trip included DH, our two DSs, and me, along with my parents. We flew to MCO, and took a Mears van from MCO to Universal and stayed in two family suites at Cabana Bay. We stayed in early May, and Cabana Bay had literally just opened. It was amazing! Very clean, food was very good, and the family suites were great! We did both parks at Universal over two days, and really enjoyed it. However, this was before the large Harry Potter expansion, so we are anxious to go back to see the new HP segments that weren't there when we went. We loved the butter beer, and the rides there were fun. However, we had never really experienced so many simulator style rides. The technology for those are amazing, but my folks, DH and I had to really pace ourselves because the simulator rides made us somewhat seasick. Of course, our boys had no problem with the simulator rides! However, the boys were young and timid enough that we didn't brave any of the roller coasters...another reason for going back again.

. My folks did the HP fly-on-a-broomstick-ride with us and they were DONE for the day. It was way too intense for them.
We then transferred to WDW with another Mears van (I would highly recommend them...they were punctual, professional, and had a van that fit all six of us and our luggage) and stayed in a 2 bedroom villa at OKW. I'm really glad we did Universal first and then Disney. While we enjoyed Universal and we definitely want to go back, their customer service and the overall experience is nothing like WDW. We stayed 4 days and had 3 days in the WDW parks. It was amazing to share WDW with my folks, who hadn't been since I was a kid. We loved the 2 bedroom villa set up at OKW, and the rides were way more to my parents' liking.
Whatever you decide, have a great time at US and WDW!