If you know anything about Silicone oil, you know that a well manufactured silicone is resistant to viscosity changes over a wide range of temperatures; the extremes on both sides that we NEVER see on a racetrack...unless you race on the south pole or on the planet venus or mercury.
Those drivers that choose one oil over another may do so because of sponsorship, or the fact that often times different companies 60 wt is slightly heavier or lighter than another's. Like I said, I see no difference between AE and Trinity oil. However, I do see a difference between those and Losi oil. XRAY oil has an even further gap; their 30 wt is close to a 45-50 wt from most other companies. It all comes down to different ways they rate their weights and that allows you to fine tune your car. It has nothing to do with brand X thickening or getting lighter in low/high temps and brand Y not.