I am going to be installing ~1400 sq ft of 3/4" x 4 1/2" engineered
plank oak hardwood flooring. I am going with the 3/4" stuff because it
has a fairly thick wear layer, so that it can be refinished several
times. I haven't bought the stuff yet, but I have been reading. The
installation will be over 3/4" T&G plywood for most rooms and ~300 sq
ft will go over a below grade (4' below) concrete floor. The concrete
floor has never exhibited any moisture problems.

I am interested in comments and hints from those who have used 3/4"
prefinished engineered wood, particularly from either Capella or
Muskoka/Tembec. I would also like to know if there were any quality
problems with these two companies, if you used their products . (I
can't find much pro or con discussion on the net.)

Since I expect that I will be doing the job over several months, I
intend to buy rather than rent a pneumatic floor nailer (PortaNailer)
to nail the planks to the T&G. According to both manufacturers, this
is acceptable with this thickness.

Several questions:
How well does the engineered stuff nail?
If you have used Capella or Muskoka, how was the material? Was there a
lot of bad pieces? Was the grade what you expected? How well has it
held up to traffic?

I don't feel like laying down underlayment on the concrete and then
nailing the planks down. This will raise the floor by 1 1/2". I think
I will be gluing down the planks directly to the concrete. If I have
to nail to underlayment, I think I would go with the floating
underlayment method which lays down two staggered layers of 3/8"
sheets nailed or screwed together, and nail or glue to this. Anyone
tried this? It does not seem to be a very common method.

Anybody glued down on concrete using the 3/4" planks? How bad was it?
What did you do to make sure boards were tight fit?

Roughly how long can I expect it to take me to complete a good sized
room. I am reasonable handy, and I have most of the appropriate power
tools; I do intend to buy a miter saw to supplement my table saw.

Any other hints I can use to make the job go easier?