I usually train in 19mm drop Brooks shoes and they are what feels most comfortable, but are around 10 ounces. My Nike Pegasus size 9's are also around 10 ounces, and feel a bit faster. I encounter a problem when I was racing with spikes for the first time as part of a time trial my team and I did where I was twisting side to side and having ankle problems the entire time. My feet couldn't find traction on the grass for some reason! I wasn't running incredibly fast either, maybe only around 5:50-6:00. Should I do my races in the Nike shoes? I am concerned it is only mental and that I would actually be going slower in the much heavier shoes but feeling a bit more comfortable. What advice would you give me? Should I try to buy a spike with a thicker plate, or just scrap the idea?