as for the raspberry pi debate
RasPi 2. 900mhz
1gm ram
RasPi 3 1.2ghz (33% increase)
1gb ram
33% increase in processing speed in just 1 year..
say rasPi2 could handle 2000 signature verification's every couple minutes.(understatement used for basic maths)
rasPi3 can handle 2660 signature verification in the same time.
Wait; that doesn't take into account the quadratic growth aspect. The correct calculation is, if rasPi2 can do 1 sigop in t and 2000²*t in a couple of minutes then rasPi3 can handle 1 sigop in 0.75t (maybe) and so in those same couple of minutes we have to solve;
X²*(0.75t) = 2000²*t
X=2309
Certainly a nice increase but not 2660. Does sigop verification scale linearly with GHz?
your assumption that quadric wont be solved in april.
also if 1000 has 33% increase=1333
2000 =2666
so i was using single sig before april(i even bracketed that i understated it for simple maths) and comparing it to scaling after april using technology available in april and code changes after april which make th quadratic debate meaningless
but ultimately my maths was simplified so will leave you to do the more detailed maths