I would tend to apply it over the pre-asic era to calibrate a scaling factor, and over the post-asic era to make an estimation. It's just a price-of-electricity estimation of a support level. I should add a Bitcoin price factor to test correlation to historical price:
(H*(T - aR) * b + c)*B
a, b, c are the parameters to fit. Since I was going from a one parameter model to a multiparameter model, I thought I should remove the ratio hack as no longer useful, thus eliminating the time window stealth parameter.
Adding a hype factor: Use Google trends on "Monero" to obtain
(H*(T - aR + dG) * b + c)*B
OK, so for the legend
H=Hashrate
T=Transactionvolume
R=Reward/Block
B=Bitcoin price in $
a,b,c,d="random" scaling factor
(427mh/s*(100tph - 4XMR/block)* 0,000001)*6600$=270,5472$/XMR
Other inputs are welcome

EDIT: Calculating the same with your first given calculation model would equal to
427mh/s*100tph/4xmr/block*0,000001=0,010675
BTC/xmr