Go for it! I think you'll find the experience on HAL and X to be a bit more upscale than on Princess, but the only way to find out is to do a cruise for yourself.

Frequent cruiser perks are quite a bit more limited than those offered by hotels and airlines. The experience you get on Holland America will be equally excellent on your first cruise and your fiftieth, for example. You may give up a cocktail party and free internet (for example; I don't know what Princess platinum actually gets you), but to a large extent your cruise experience is dependent on the cruise line and the itinerary, not any perks.