Been using the trial version of True Pianos on my Abacus for some time now and it is easy on CPU as well as using little Ram.
Once loaded in the host or standalone (A few seconds) all the piano sounds are available instantly. (Due to the techniques used in the program, no loading of sounds is required, they are just instantly playable)
Sound modelling is definitely the way of sounds for the future. (Bye Bye Giga, you were good in your day but now its time to plan your retirement)
Enjoy whatever you play

Bill

PS. I like the Diamond Classic voice best