I have never used a footprint with my lightweight tents, just checked the tent site to remove rocks, sticks, pine cones before pitching (you need to do this whether or not you have a footprint). That will save weight, too. If you think you absolutely must have a footprint, get a painter's plastic dropcloth and cut to fit, about 2" smaller than the tent floor on each side. Or, more durable, the polycro plastic used for storm windows/doors. Either is lighter and cheaper than tyvek.

I have used several Tarptents, although not the Contrail. They are excellent quality and customer service is outstanding.

I have no familiarity at all with Big Sky tents.

If it makes any difference to you, Tarptents are made in the USA, while Big Sky's, I understand, are made in Asia.

One thing I'd do before deciding is to take the manufacturer's dimensions for each (from their websites) and do a mockup of each on the floor using masking tape, string and strategically placed furniture. Then crawl inside and see how much room you have.

There's a new version of the Contrail coming out, called the ProTrail , for which you might want to wait--it's supposed to be available next month. IMHO, the rear end looks like a definite improvement over the Contrail.