This is an old post, but I'm going to respond as others may find it useful.
I have sold two 58 Tiaras in my career. I sold Hull #1 at the Miami Boat Show when it was first released and I sold Hull #14 or #15 a few years later.
The 58 is a great boat in my opinion. It has a nice interior layout, although small for a 58' boat. It compares more in size with the old 52 Sovran in terms of interior space, although the 58 is laid out in a much better way. The 58 is fast, nimble and fuel efficient. It is truly fun to drive

.
The Triple IPS set up is nice. Yes, you have three engines and drives, but those three engines are much smaller and far less costly to maintain than two larger Diesels . The drives are another matter however. The drives are expensive to maintain and do require a fair amount of service (Oil changes, anode replacement and periodic adjustments) . In the end it is a wash between the savings on engine maintainence and the more expensive drive service. The triple IPS set up had some issues when the 58 was introduced. There were some drive overheating issues (the twin engine installations on the smaller IPS boats did not seem to suffer this issue

). Many of these boats have had drive coolers installed since they were first released. If you are looking at a pre-owned 58, make sure you get the service records and that the drive cooling issues are resolved. Pay special attention to the sea-strainers and corrosion around the sea-strainers. The original sea-strainers were notorious for leaking. The sea strainers are located above the alternators, so the water would hit the belt and get spun around the engine room. As long as the sea-strainers have been updated and the corrosion issues addressed, this should be a none issue.
IPS with joystick control is a marvel. Unless you are a master inboard operator , able to dock the largest vessel in high winds and current with ease, you will appreciate the IPS system. As far as the front facing inboard propellers, I have had no issues with them. If you run aground, it matters little where the props are mounted.
The 58s are light. They were built light for better fuel economy and better performance. They are not heavy sea boats. If a majority of your boating is slogging it out in 5' to 8' seas on long trips, the 58 is likely not your boat. If however you are a fair weather boater (most of us are - come on and admit it!

) and only hit the rough stuff occasionally, the 58 is a pleasure to operate and you will appreciate the low fuel burn and high speeds.