I would run the sa10 in a ported box tuned properly. And save some doe till u can sale the e10 and buy another SA. The box requirements are "almost" the same for the e series and SA series but that "almost" is the difference between good and bad.
I have run both the e series 15" and SA series 15" and as far as subjective listening at lower power levels say 400-500 watts per sub I could not tell the difference between them. The difference is that the SA's are damm near indestructible under 1000 watts rms and the e series got stinky at the same wattage really quick.