This topic has raised many good points. so I'll address what I can.
My biggest bugbear first. For those with UHF please remember that Channel 5 'Emergency' Repeaters are set up at various places around the country and most of them are monitored by volunteers.
Because of this, it is very important that no-one transmits on Ch 5 or the Duplex pair Ch 35 unless there is a genuine emergency.

There is a Ch 5 repeater up on Mt Glorious and it is monitored by ACREM.
http://qld.acrem.org.au/ A good repeater listing can be found here
http://www.vkham.com/Repeater/uhfcb.htmlIn the Brisbane area there are several repeater stations, Ch 7 (VHQ07)
http://www.vhq07.com/at Mt Glorious, CH 8 at Oceanview, and there used to be a CH2 at Wavell heights, CH 6 on the Sunshine Coast, Ch 4 Laidley, Ch 1 on North Stradbroke and a couple down the Gold Coast. And I believe there is a CH 7 up in toowoomba as well
As has been said, UHF repeaters are very handy if you need to talk to some one over longer distances. I can see this being handy if you have the groups all setting off from different locations to meet up somewhere, using the repeater until you get closer to each other would be handy. Also on a long trip where the group may get broken up, knowing a local repeater station may mean you can flick to the repeater on loss of contact to regain contact with somone who may have fallen behind for various reasons. Some large rural properties set up repeaters to keep in contact across the farm and some do frown on you using "their" repeater, but it is not illegal to use them, as it is a public class licence that allows them to set up 'their' repeaters.
CH7 (VHQ07) is usually very busy during the week and there are some "power" stations, with quad directional antenna 16 or 21 element arrays, the can swamp/dominate the repeater from time to time. It's big benefit is the coverage area which is from the Gold Coast, west to Toowoomba and North to the Sunshine Coast. I used to use this channel a lot when I was running around doing servicing work in the South-East. Made some good friends through that. (one of them another ST1300 owner)
Ch 8 suffers badly from Truckers 'going down a couple' for a private chat on the Bruce and thereby going to the input channel of Ch 8. and this is where it is bad manners to transmit on 31 to 38 and with the new 80 Channels 71 to 78.

There is some good reading here on the ACMA website.
http://www.acma.gov.au/WEB/STANDARD/pc=PC_1265 This one explains repeaters
http://www.acma.gov.au/WEB/STANDARD/pc=PC_1265#repeaterPart way down this document
http://www.comlaw.gov.au/Details/F2011L00862 it explains the new 80 Channels, but as has been said before, they have slotted them in between the old 40 channels so Ch 41 slots between Ch 1 and Ch2, and Ch 42 between Ch 2 and Ch3 etc. At the moment the old radios have a 25 kHz spacing with no more then 16 kHz bandwidth and the new ones have 12.5 kHz spacing and no more than 10.1 kHz Bandwidth.
In a few years time, 30 June 2017, the old 40 Ch radios are expected to be retired and only 80 Channel radios with 12.5 kHz channel spacing will be legal. Some of the old radios, the more recent ones, can be reprogrammed to the new channel spacing to remain legal.
One other point, UHF repeaters cannot legally be connected to each other, so once you out of range of one, that's it.
Hope that helps.
Gadget
