Do 180g vinyls sound better or is it a myth ?

OMG...there are so many misunderstandings represented as "facts" on this thread. Please review the Nyquist–Shannon sampling theorem. XLR connectors do not necessarily indicate a "balanced" transfer of signal. A vinyl record only stores information in 2 axes (with respect to time). There is no such thing as a "balanced speaker" - only balanced amplifiers.

To address the OP's question (Does the weight of the vinyl make a difference to overall sound quality?) the answer is "maybe"?

Assuming every other variable is held constant, a more material using in a record may make a difference. For example, on a very lightweight platter with a tendency to ring, additional material in LP may reduce said ringing. This also may disrupt the intended design characteristic of the playback system. So was this change "good" or "bad"? It depends...hence the definitive answer "maybe".

From my experience, LPs with more mass tend to be less prone to warping. So that's a net positive. Does this benefit outweigh any realized negatives...that's up to the listener.

I'm not going to get into which sounds "better". I've heard great and awful examples of both.

It’s a moot question. Has any LP been offered in two versions, the only difference between them being the weight of the pressing? An LP offered in a 180 gram version is different from all other versions in ways other than just the 180 gram weight; the source, EQ, limiting, mastering, plating, quality of the vinyl, etc.

Most of my listening is not 180 or 200 gram vinyl.  However, some recording are very hard to find in nice condition.  For example the rca living stereos are very good recordings for the most part, but most are destroyed.  classic records made some very good reissues and took great care in the process.  If you have a lot of disposable cash and can afford to buy 10 copies before you get a listenable one, then by all means original shaded dogs can be great indeed.  That being said, most of the time, the original pressings are the ones to have most of the time.

Thanks for all the info, it's great to hear all your views. All this info is giving me a better understanding on everything. 

Thanks again 

Just another scam to get your money. Something could be pressed on 500 gram, but that does not mean it will sound better. I too have given up on these 'new' re-issues. They are warped, full of noise and don't live up to the hype. I like to look for clean original first pressings.  I have bought 180's and 200's till I can find a good first pressing. Plus that's part of the fun. Some of the Rhino's, Analog Production and Audio Fidelity's are pretty good.  To me the new Mo-Fi issues are bad. They don't compare to the old original Mo-Fi's.