Just another point to add to the discussion, safe-n-sound are the only brand that actually test there seats so in my mind they are the only ones that should be on the market.
Britax who own Safe & Sound also manufacture pretty much every car seat on the Australian market - and all of them have to pass the tests to be sold so I'm not sure what you are talking about. They also own the testing facility and are on the board for Standards Australia, which is why the standards are so heavily biased in favour of SNS. I wouldn't put too much stock into a brand name if I was you (or Standards Australia since we lag behind the rest of the western world in terms of new seat developments and rear facing age requirements).

We have a travel system capsule for our pram and its great, we use it all the time. The capsule is rated to 13kg so Oliver will be in it until around his 1st birthday but obviously your milage will vary depending on how heavy your child is (length is moot, as long as their head is within the seat it doesn't matter if their legs hang out). I use the pram seat for walking during the week and we usually just take the chassis and capsule on the weekends to save room in the car.

I found the capsule much more snug and secure when Oliver was a new born as compared to the convertible seats in my mum and MIL's cars where he seemed tiny and lost. Plus, we can settle him into the seat in the house, cover him with a blanket, then walk to the car and just drop and lock it onto the base.

We bought ours because we plan on having a couple more babies and expect to get more use out of it before it expires. The hire capsules near us are the Polo capsule which only goes to 9kg so its worth checking that.