No advantage unless you want to pursue a GA licence at some point down the road. Even then, you could still just do your GFPT then. I have a GFPT and an ASIC card... they both sit in the bottom of my drawer unused.
10 hours flying time in an RAA registered craft, minimum 1 hour solo time.
Yes, RAA is not a transfer so much as an additional certification. You keep all your GA hours in your logbook and they will still count in the future. Depending on the timeframe (we're talking years here) you may need to complete an instructor check and a new ASIC card or medical.
No implications as far as I am aware... not really sure what you are meaning in this instance. RAA aircraft are able to be flown with either a PPL and above or an RAA Flight Certificate. It is the RAA equivalent of a PPL, and limits your flight to daytime VFR, 1 passenger, craft totalling (mostly) not above 600kg MTOW, flight not above 10,000ft and within Australia. In other words... a fairly good chunk of airspace!
As I mentioned before, I did my conversion to RAA from GA at GFPT level after deciding not to pursue a CPL career but still wanting to fly privately. RAA was the best option for me, and I think for most people. It is cost efficient and much better on the side of aircraft ownership, eg no $5k 100hr checks from a licenced aircraft mechanic, simply get your Level 2 cert and do it yourself.
I would recommend the closer place with more aircraft... not that I am familiar with either but that sounds like a good recipe for flying regularly. Flying regularly is the key to getting things done efficiently, or you simply spend 50% of your flight time becoming reacquainted with the craft.
At 6'5" you may have some trouble in some RAA craft - I am 6'2" or 3" and find a Gazelle, for example, to be fine on headroom but very tight on legs; a 2hr flight is all I can manage in one and I'd rather 40~60 minutes. Ask the instructors what is available and if you can see what you fit comfortable in. Make sure controls are not an issue while you are doing so - ensure you get full range of movement without having to adjust your position greatly, or preferably at all.
Cheers - boingk