Pretty sure jakar's point was that it's not an issue, because it doesn't affect things as long as it stays BG, and even if we do eventually go SG on the suburban network it's no more difficult to fix than it otherwise would be. I don't think it was suggesting that we actually do convert suburban passenger trains to SG any time soon.
Spot on Simbera. I actually didn't think my post was too hard to understand, but to clarify for those who missed the point or immediately took the worse case scenario option (which seems to be a common trait on RP), all I was saying (in response to Nightfire's suggestion that all suburban platforms would need to be rebuilt to be on the same side of the track) was that if the line was to be made dual gauge and as long as the SG was used purely for freight then the stations would not have to be touched as the SG loading gauge would be within the BG loading gauge. In the case of Brisbane and Perth, the stations would be a factor as you are going from a smaller to larger loading gauge and therefor to make life easier they would need to be on the same side.
I then went on to say that if (and to reiterate, only if) SG passenger trains were introduced it would probably be a good time to gauge convert the entire line instead of tinkering around the edges so to speak and rebuilding stations just so you can run both BG and SG passenger trains. Am I suggesting this should happen? No. Would it cost a bucket load of money? Yes. Would you have to gauge convert the entire Melbourne track and fleet? No. Would it be a pain in the backside in regards to suburban fleet and track separation etc? Of course it would. Would there be benefits for freight on the Hastings and Gippsland lines? Yep. Would the benefits outway the cost? Don't know but given the cost of anything "railway" these days most likely not.
I hope that clears up where I was coming from for those that didn't comprehend my initial post.