sizeing a mini split

[nokiasixteth]

I had originally wanted to get a mini split . But the more i look at mini splits the more im thinkin on just getting one of those. If the geothermal had some that was ductless as well i would prob lean toward it . But right now i am heating with space heaters alone . Theyve been eating up some electricity lately with these oddly cold days weve been having here
Not being really familiar with min splits ive been thinking on a 1 ton mini for my main living space and later on another for the other part of the place we rarely go into .
The whole house is around 1050sq ft so i may be a bit over kill. Fixing to add another R15 to the attic and insulate the outside walls wich has no insulation.
Any one have any good suggestions that theyve had with minis. Main that we stay in is 556 other part is 418 and the wash room is 80 sq ft but it stays shut up most of the time.
Found 2 mini splits 1 is 15 eer 623 and the other is 1130 both are plus freight.
Would it be worth it to fork out the extra cash on the 5 extra eer. Or would that play much of a difference