I have a large collection of TI calculators: TI-83, TI-84(Silver), TI-89(Titanium), TI-nSPIRE CAS, TI-nSPIRE CX CAS.
The first thing I have to say is that the new nSPIRE CX and nSPIRE CX CAS are amazing calculators; they'll do everything you ever need in a handheld calculator.
The question is: "will you be allowed to use them?" Different schools and different tests have limits on what calculators you can use and some of them haven't updated their policies to address the nSPIRE CX line.
I've been able to use my TI-89(Titanium) and TI-nSPIRE(s) from Calculus I (when I purchased the 89 for it's CAS capabilities) through my upper level Math and EE classes.
I don't understand policies that limit calculator use at school... Do you really want the engineer on your project doing his math by hand? (Or trying to use a calculator/software for the first time since he didn't learn how to use them in school!)
No matter what calculator you get now, eventually you'll have to move on to MATLAB or some other software package to solve problems.
One other caveat, most of the textbooks are still written for the TI-83/84, so if you get a different calculator that isn't preferred by the school, you'll be teaching yourself how to use it. (My Engineering department recommends the HP-50, so I've been on my own to translate operations onto the nSPIRE--fortunately the function names are similar, even if the keypresses are very different!).