Think of it this way. Imagine if you will that your barrel is made out of plastic. The shorter it is, the harder it is to flex. The longer it is, the easier it is to flex. If you have a 24" barrel it will flex more when you shoot it. If it were 7" long it won't flex much at all. So for longer barrels you need a thicker barrel to keep it from flexing. Thicker barrels mean heavier barrels. Really heavy barrels will flex your upper reciever. Heavier barrels take longer to heat up, conversely heavier barrels take longer to cool down. Hot barrels flex more. More flex equals less precision.
if you plan on actually going out and schlepping it, you need to balance weight and overall barrel length.
if you want a long range benchrest shooting, weight isn't all that important.
Assumption is the mother of all ****ups.
Know what you know, Know what you don't know. -Paul Pedzolt
"Jack of all trades, master of none, though oftentimes better than master of one" -Mynshul