[Brian Duff]

Ralph,
When your prospective new boat goes to survey, hire, as Brion suggested, a competent rigger that works with rod to do a complete survey of the rigging. They can safely disconnect shrouds and open fittings (as long as their not peened shut) and clean and inspect the cold heads, which is where cracks often form first, and they can inspect the rest of the rig for problems as well. A survey like this will probably cost $150 - $300+ depending on weather all the fittings (top and bottom) are inspected (takes longer) , and your location. This I feel is a good investment as re-rigging the boat may not be in your budget, or if there are problems found you may be able to re-negotiate the price .
Owners are normally reluctant to let buyers start taking the boat apart them-selves, but a rigging company, with proper insurance and experience would be a choice they couldn't say not to, as surveys are standard practice when buying a boat.

Tobin,
I know you asked Brion, but I'll give my $0.02 since I am already writing here.
Yes, you could switch to rod rigging, you might run into compications such as having to bush holes for pins and changing your spreader ends, depending on design. The question is why you would want to do that before a carribean cruise. Wire is simple and lasts well, resists fatigue better and can be repaired or replace by more yards throught your trip. Rod rigging requires special and expensive tooling, which many shops dont have, and it is difficult to carry spare rod and fittings in the hope that you might be near an equipped yard when you need a repair. I am not a big fan of rod, and wouldn't suggest switching to it. Go with wire and mechanical fittings for an easily assembled, repaired and long lasting rig.
Not sure what fittings you mean to replace later, but if you are speaking of tangs and bolts and sheaves and lights etc... yes you could replace all that later. but if you mean the end fitting that terminates the wire then no, you would end up replacing the wire again because most fittings have to be cut off then your wire would be too short.
Unless you went with the rod, in which case cutting off the cold head and re forming with new fitting on will usually leave enough length to be practical solution.
Good Luck.