Just bought a new house and wondering if I could get some help making sure I buy the right softener? I've done a lot of research both here and several other places and I think I understand most of what goes into correctly sizing a softener, but here's what I'm struggling with. Right now, it's myself, my wife, and our 17 month old son. We have twins on the way so given the lifespan of softeners these days I'm not sure if I should go with a smaller unit that will suit our more immediate needs or whether I should go ahead and go big now and size for a full blown family of 5. I think I've convinced myself it makes sense to go ahead and go bigger now so I've been looking at either a 2.0 or a 2.5 unit with a Fleck 7000sxt controller.

Here are the facts regarding house and water quality.

3800 sq ft.
4.5 Baths

Water sample tested at Leslie's pool supply

Chlorine .93 ppm
Alkalinity 108 ppm
PH 7.7
Hardness 354 ppm (21gpg)
Copper .2 ppm
Iron 0

Given the details above I guess what I'm looking for is some advice on which direction I should go. It makes sense to me to go ahead and buy for the future but I want to make sure that there aren't any downsides to using a larger unit now when our water usage is not gong to be as great. If this is not an issue should I go with the 2.0, the 2.5, or should I go ahead and go really big with a 3.0 unit?

I'll be ordering online in the next fews days so any advice you can offer up would be great.

Thanks in advance.