Pressurised Barons were introduced for the American market where professionals and business people wanted to fly high and in comfort over the Sierras. The pressurised Baron that i had 6 yrs experience with was extremely high on maintenance costs both fixed and unsceduled, much heavier than the std 58 (look at the fuse rivets...mind boggling and the price to replace windows and screen is money most only dream about!). Strictly light 4 placer and if my memory is correct i think the TBO was 14/1500hrs. Performance wise below 10k was much the same but very very smooth to fly. The sound, well, even more so.... typical Baron.
Check the resale on P's on the Continent and in the USA and they are usually or were, considerably lower than the std 58.FWIW, PERSONALLY, i wouldn't look at a 58P for Oz ops.