After the weakest chromatic dragon, here's the weakest metallic! Brass dragons have the fire subtype, which is a net gain in power. Their breath weapons are a line of fire (bad) and a cone of sleep (quite nice). Skills are Bluff, Gather Information, and Survival.
The 1 HD these have over white wyrmlings gives them better mental stats and an extra point of AC. Their main breath weapon is arguably worse than the white's, but the sleep breath definitely outperforms both. Icewalking is swapped out for Speak With Animals at-will, and the white dragon's swim speed is dropped. Also of are Hide and Move Silently, which Brass dragons don't have as class skills.
To me it seems like the abilities lost and gained are nicely balanced out by the extra HD. +1 LA is necessary, but nothing beyond that.
We shall now return to our regularly scheduled chain of -0 LA's.
If a 10th-level ability amounts to 'you are medium now', and if you are glad to have it... why the hell weren't you medium to begin with? -0 LA.
Brass dragons gain abilities at too slow a pace: nothing new there, so -0 LA for all others shouldn't bear explaining. However, one interesting thing I feel like pointing out: the Summon Djinni ability of a great wyrm brass dragon doesn't actually have an usage limit, so they can have a permanent army of 600 djinni flying around and creating stuff. It's not too relevant at those levels, but it does allow for the creation of 25 cubic feet of wine a round: maybe spend your outperformed epic leveled days in endless wine-gorging?