Alistair, the reel up to the 4000 size are a different series from the SW series. The SW series is a heavier duty series of reels. This current SW series was only released in 2008 so I doubt there will be a new one for a while. A high profile like the Stella would nearly always be announced at the Japan Tackle Show. The show has come and gone so while I cannot be 100% certain, I doubt there will be a new SW reel for some time but this year at the very least.
None of us have been able to discern any difference between the JDM SW and the export SW. There have been rumours about a different spool or different layers of rust proofing etc but I cant confirm any of these. All I can tell you is that I have a JDM and an export 10000 and I can't tell any difference between them. There are always rumours of problems with reels and sometimes, these take on the stuff of legends. There have undoubtedly been some cases of problems with reels as there always are but I think these get blown out of all proportion. Just make sure you get a reel locally then you know it will have a warranty behind it.
If you want the reel for jigging, then I'd suggest you go the PG. If you want it for popping, go the 5.8. I'm not sure what you mean by shore jigging though.
If the fishing you are doing are for big critters and you intend fishing PE8-10, I'd suggest you look a an 18000 or 20000.