USB 2.0 will definitely load Styles, Midi's, .Wav, or whatever, much faster than a USB 1.1 interface will. The question remaining is whether Yamaha's other components on the T3 are themselves further "optimized" to take advantage of the USB 2.0 interface on the T3. Depending on whether the T3 Motherboard, CPU, Memory Bus, etc., are improved over the T2 is important in the scheme of things. Regardless though, the potential has already been vastly improved with the inclusion of USB 2.0 on the T3 i.e. USB 2.0 = up to 480Mb/s transfer rate vs. USB 1.1 = up to 12Mb/s transfer rate.
Bringing up Styles from the Hard Drive is probably going to be about the same in my opinion, although I could be wrong about that.
One way for quicker response from the Hard Drive is a reduction in access time to the Hard Drive itself, which depends significantly on the rotation speed of a given Hard Drive. In other words, if Yamaha allowed faster Hard Drives to work with the T3 it would also improve the access time it takes to bring up Styles from the Hard Drive in my opinion. But I don't think you can use 7,200 RPM Drives on the T3 and instead, I believe 5,400 RPM Drives are still the current limit.
Best,
Mike
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Yamaha Genos, Mackie HR824 MKII Studio Monitors, Mackie 1202 VLZ Pro Mixer (made in USA), Cakewalk Sonar Platinum, Shure SM58 vocal mic.