A friend did a more testing, and ETH+LBC in R9 380 is a lot worse then ETH+ SIA
his rig stats are:
4x380
ETH/LBC = 70/55MHS
ETH/SIA = 85/900MHS
Looks like LBC is way to GPU intensive for R9 380 and maybe other card, impact on ETH is just to huge to have any benefit mining LBC and losing on ETH side more
Depends on Sia and Lbry price. For me it is a bit more profitable to dual Lbry, but there are recent crazy price jumps for both coins. Also dual mining LBRY takes ~15-20w less power per 470/480.
You need to recalculate again, lbry is not if any more profitable then mining sia, but with drop on ETH you are losing to mutch (4x 380 lost 15Mhs on ETH??) maybe the problem of ETH drop is more seen in multi GPU rigs
Currently, for you, it is a lot better to do sia, even without the drop in hashrate for eth. For me, it is slightly better for sia, though an hour ago it was better to do LBRY, and yesterday probably LBRY (sia difficulty has not adjusted for recent price spike, and likely many are trying out dual LBRY, which adjusts diff every 4 minutes). Just saying it all depends on diff/prices, but currently they are close enough that it depends on the card.