Has anyone else experience poor durability with the outsoles of the GR7s? I am a long time user of GR5s and GR6's and I normally get five months of use out of them with six hours of play per week. However, my 7s wore out in half of the time--2.5 months. They were super loud and squeaky initially too on the court which was unusual. My conclusion was that the pair of 7s I got had a softer, less durable rubber. Has anybody else experienced this? Asics technical support said the 7s have the outsole as the 6s which I find hard to believe based on my experience with the noise and durability. Anybody recommend a similar shoe with good cushioning for my sore knees with a 6 month warrantee? I need a replacement shoe but I don't want the 7's if they are less durable.