Like I said with a few tweaks you can get rid of the repetitive ground textures (use VOZ1.8 for example), water textures can be replaced to look similar (not exactly) like FSX water (which isn't that good IMHO), clouds can be mad HQ and there are still tons more add-ons for FS9 than there are for FSX. Your claim that FS9 is only good for high altitude IFR flight is ridiculous. FS is just as good in low VFR flight as FSX supposedly is. There are add-ons to replace the autogen to make it look denser and better.
PS Hi Paul. Just sticking my nose in other people's business....
Sorry but I have to disagree. In case you didn't notice, I know FS9 very well because I flew it for MANY years, just like you. And unlike you apparently, I have also flown FSX for many years and I know its addons too, both freewares and paywares.
Also please do not modify what I said. I haven't said that FS9 is "only good for high altitude IFR". I said that IFR flight to major airports is the only domain where the FS9 experience can be superior to the FSX experience.
When it comes to VFR flying, sure FS9 alreayd offers quite a nice experience, but the experience offered by the scenery possibilities in FSX is way greater, thanks to better ground textures and better autogen. And the photosceneries make it even more true. The smoother FPS offered by FS9 over major airports is its one and only advantages on FSX.
When it comes to military flights, the problematic is the same. The better world rendering, the better plane rendering, the additionnal features (moving carriers, shared cockpits etc...) make the FSX experience much better than anything you can get in FS9.
The smaller number of available freeware addons for FSX is not a problem anymore. It was a problem in the first years perhaps, but nowadays nobody is complaining about the size of their hangar or scenery library

Once again, I do not see for the above mentionned points how FS9 could offer a better experience than FSX. That doesn't mean FS9 is bad. The question was "is it worth it", the answer is "it depends what you intend to do". Since Raoul stated that liners might not be his main focus, then my answer is "no, FS9 will not bring you anything that FSX is not already providing".