Howzit Karl, welcome to GT Popping bru... always good to have another Saffa on here!
There is no quick answer to your question mate... and as you so rightly put it, its a bit of a "how long is a piece of string?" scenario...
But I can tell you this:
* Most of us take far too much tackle on a trip.... somewhere between 20% and 75% too much in my opinion
* No matter how much you take, you will always have too much of one thing, and not enough of what you really need... its a fact of life and a law of nature ( that doos Murphy at work as usual! )
* You need far less than you think, usually....
* Most of us fisherman, Poppers and Swoffas included, love tackle, and the collecting/hoarding/acquiring of it... and there are very few types of angling that have more cool gear, and desirable kit, than GTpopping.... so we always try justify our tackle addictions by taking as much as we can on our trips, because we've paid for it, the wife would kill us if we didn't at least attempt to use it!
So, while the above is probably useless trivia, the below might help.
Heavy Popping - If you are going with inexperienced/less experienced guys, this facet of angling will probably see less action as its alot more labour intensive ( casting heavy lures in the boiling sunshine is hard work )... While the rewards can be amazing, Maldives in general is a small to medium size GT fishery... that being said, there are big fish there, but for the most part you'll be dealing with fish in the 10 to 20 kilo region, which doesn't require very heavy tackle.... But you want the heavy stuff for when you do potentially run into some big buggers... but you probably don't need dozens of large lures for a trip like this... Between 4 of you, I would look at taking maybe 12 to 16 "Large" poppers/Stickbaits for the heavy gear...
Maldives requires alot of long distance casting, so your medium long casting outfits with lures in the 40 to 100gram range are gonna get the most action... this is a case of fishing anything from 30lb to 80lb braid set ups, and 40lb to 120lb leaders... this is where your GT Ice Creams and such come into their own.. relatively cheap, cast like rockets, can be fished fast over large areas of water, and they slay the fish... add some smaller stickbaits and poppers, and you set... So with 4 Anglers, I'd say you want at least 15 lures ( 3 different sizes, 5 of each ) in this range per person, so 60 lures total.
Add some jigs, some plastics and you are up around the 100 mark and you sorted...
If you fish smart ( don't fish too light, rather go a little heavier than you normally would to prevent bust offs etc ) your loss rate should be minimal, and you should last the 10 days...
Hope that helps... unfortunately there is no set formula to go by, thats just my advice... \
It would be worth getting hold of Nick Bowles and chatting to him... Nick has run numerous charters round the Maldives, and is one of the most experienced guides and GT Fishos out there, so would be able to advise you accurately I reckon...