Arnie, normally I'd wait until one of the experts on here answered but since you're going to be calling them back tomorrow, I'll give you my view. Most, so called, servicemen, salesmen, mechanics or whatever, normally use a rule of thumb. Especially in the South. They normally use 400 to 500 sq.ft. per ton for A/C. No way that that is accurate. I don't know what they use in your part of the country. Have someone do a load calculation on your house. This takes into account the amount of windows, the insulation in the house, the square feet, the mean temperature, type of siding and numerous other factors and requires that they measure the house. This way the units are sized for the specific house into which they are being installed. I think that anything less than doing the load calculations is just guessing. If you don't you may end up happy and you may not. I'm sure that they are going by what they normally see in that area but down South, a two ton A/C wouldn't cool a 2000 sq. ft. house. Not sure about N.J. If it's oversized, you'll end up with excessive humidity and undersized, it'll work too hard and you won't get proper cooling.
Or since you're just converting from gas to electric and if you've been happy with what you've got, go back with the same sizes that you have now. A ton is a ton and a BTU is a BTU and it doesn't matter if it's electric or gas.
I would go into blower door testing, but you didn't ask about that. Good luck.