...At what point does solo mining become worth it, when you can generate at least 1 block per day?...
At the point where your revenue covers your expenses without you being out of pocket (i.e., if you have a $2,900 monthly electric bill and BTC/USD is $2,900, then you need no less than 1 block per month just to cover your electric) and then the profit margin you want to have on top of that.
Well I don't know if you've looked up the profits that the Antminer L3+ will bring when it ships out August, but right now they give you a 45 day ROI which of course you know is INSANE.
So you're saying that as soon as you have your mining equipment payed off (you hit ROI), you should start solo mining? It sounds like you're saying you should solo mine as long as you're mining at a profit ($2000 on electricity, $3000 in LTC for $1000 a month profits), but that wouldn't make much sense, no? That would mean everyone would always solo mine.