HP Prime vs Ti Nspire CAS CX II

[bmr]

I have both calculators with firmwares updated to the most current for each. I love testing them against each other for complex calculations. I have been running a sigma with about 40 iterations, where in the sigma is a difficult integral that starts at two and ends at the index of the sigma. If I run the two against each other, press cntrl on the TI and shift on the HP ( to get approximation mode ) then the TI wins quite handily. If however, I switch the HP to non CAS mode and run the same calculation, the HP crushes the TI by a huge amount. I thought that while in CAS mode for the HP that if you push shift before the calculation, you are effectively in non CAS mode. Anyone have thoughts about this matter ??