About to swap out the stock crank set. My frame uses a BB86 BB, so if I go with Shimano, i can re-use the stock BB. Am thinking about a long term group swap out to SRAM. Is there any noticeable difference in spindle stiffness between SRAM and Shimano? The SRAM uses the 'stepped' GXP BB, while the Shimano uses the 'constant diameter' spindle. Thank you in advance.