Well RichTRX saved me a bit of typing!
But i think you'll base your decision after driving both types of cars and then think about what you really want to use it for.
EG- my passion is through the hills. -180sx: too tail happy and not characteristically set up for the hills.
-R32: much better balance and stable through the bends.
Then i used characteristics to base my decision, not which is 'faster'. -R32: very comfertably interior, standard seats are very functional through the bends too, Beautiful unique sounding engine, timeless looks for its age( i didnt want a sleek looking car)
-180sx: Nice interior but too cramped for me, standard seats are shoking, engine probly out performs with better torque (in stock form anyway), sounds typical but looks very nice with the right applications.
Conclusion: In the end i have chosen the R32 because it's a whole package car to me and the 180sx isn't!
: i tend to think that if you'll be paying it off and just want a satifying cheap performer, go with the 180sx! You'll get a better 180sx for your money than a R32 being a bit more expensive.
Hope that helped a bit.
Dave.