I think I can answer all of your questions: Yes, the new NTSC Slingboxes will probably work in AU because the old NTSC Slingbox worked fine for me (excluding the RF Tuner which I didn't use anyway). For the Slingbox to launch and sell well in Australia, it would need to be able to control Foxtel STBs. The HK model does a brilliant job of controlling the STBs of the two main cable TV companies there. I'm not sure how co-operative Foxtel is going to be here, and if they launched it without Foxtel support - there would be a lot of bitching. Expansys started importing and selling the HK model into the Australian market a while ago, but recently had to stop selling it. Either it was because the official launch is imminent, or because it didn't comply with Australian Power Standards (it was being sold with a UK/HK powerpack). I'm using a HK Slingbox (which is the same as the UK one) here in Melbourne and it's working really well - it even receives the digital TV broadcasts! So if you live in an area with DVB-T broadcasts, you'd be better off buying the PAL version. You're correct the only PAL/NTSC bit is the tuners - but also the resolution. If you put a PAL Composite image into an NTSC Video in, you might suffer from some cropping or just a bit of a resolution mismatch. And to answer the question about whether the video quality has improved on the 2nd Gen boxes? Only when viewing locally, eg. over WiFi. There's been no improvements to Remote Viewing.

Heres my plannedd setup .. would be interetsted if you guys think this would all plug in ok.

I have a topfeild pvrt, it has twin SD digital tuners, and it wirelessly connects to the net every day and downloads a 1 week epg (aka build your own tivo for AUS) then i setup all my auto records. Im overseas in europe working at the moment but from memory it has an adapter that splits the incoming ariel into each tuner and then a single output to the tv. That way I can record one channel while I watch another.

I would plan on running this into an input on the slingbox, then slingbox to the tv.. make sense?

That way I can have twin tuners. The question is can i program / teach the slingbox the codes for the topfeild remote?

Then I have a mac mini hoem theater that has twin SD digital tuners, i run this to another input on the tv.

I didnt have a chance to plug it into the ariel (so much rewiring) before I left to come over here but... 

I would like to split the incoming  ariel out to both the topfeild and the mac mini. therefore I would have 4 concurrent realtime tuners operating on the aerial. then run the slingbox out to the tv from these 2 devices

The advantage of this setup is that I would then have access to all my musi, video, DVD's etc etc through the mac mini plus have 4 realtime tuners running.

Does this setup make sense?, can you see any issues?

Cheers

The US PRO box does tune PAL signal. It is working in countries like Switzerland, Romania, India, Israel, Germany, Serbia - all of them PAL. From my personal experience, I would rather say that, although its tuner is PAL compatible, it provides a weaker image (good colors but lower resolution; the sound is OK). If you choose to use the tuner, don't panic if, after scanning the channels for Australia, you get weird results like: half of the TV stations with sound but no image and the other half with image but no sound, no sound at all or other similar things. Just do the scan choosing other PAL country.
I have a PRO box slinging from Romania, the main input is A/V from an old VCR, the tuner is set for Switzerland and I watch it in Canada.
If you do not know which countries use PAL, go here: http://www.psreporter.com/pal_system_tv_standard.html
I wish you all good luck. Any private message welcome.

Slinging from Romania and watching in Canada