Is this evaluation ok?
Does it have no correlation with about 32SC ~ 3min and 50BTC ~ 10min ?
Target time/block doesn't enter this calculation (it only affects what difficulty a network will end up at at a given hashrate).
Just block reward (thats where the 32 and 50 come from), difficulty and exchange rate.
another way to put per-block reward, difficulty and exchange rate together:
1 share on BTC gets you about 50/1806098 BTC = 0.000027684 btc/share
1 share on SC at a exchage rate of 0.0017btc/sc gets you ... 32/2703*0.0017 BTC = 0.000020126 btc/share
0.000020126 / 0.000027684 = 0.726990319 -> you're making about 27.3% less mining SC and selling em than mining BTC.
now... what exchange rate do we need to come out even?
50/1806098 = 32/2703*X
or...
X = (50 / 1806098) / (32 / 2703)
X = 0.002338432
you can also swap things around to suit you
X = (2703 / 32) / (1806098 / 50)
X = 2703 / 1806098 * 50 / 32
or replace the * 50 / 32 with * 1.5625
X = 1.5625 * 2703 / 1806098
... and it's still
X = 0.002338432
Wonders of arithmetic!
At the current sc diff of 3080, the break even exchange rate is 0.002664584
Interestingly, that's just about where the bitparking exchange most recent trades are happening. If the exchange rate continues to track the breakeven exchange rate (at least some of the traders must be doing this calculation, it seems unlikely to be coincidence), sc value will go up relative to btc if their respective difficulties continue to trend as they have (sc up, btc down).
The exchange rate is up in excess of 50% since last night, and it wouldn't suprise me if the trend continues, at least in the short term. With miners redirecting to sc and the high frequency of the difficulty adjustment, it could change rapidly.
Long term ( you know, like a week

) obviously sc will need to be more widely adopted to continue to track btc in terms of valuation based on difficulty.
Or not.