The quality just gets better and better, and Rusty recently has changed the way the wheels are made/cast which actaully makes them much denser/stronger. Not like they needed it, as they were twice as strong as anoyone elses effort (American Racing, etc...), in that style of wheel. The 16's are still one piece cast, while the 17's and larger are a two piece.
Rusty is a stand up guy in my book. I have been dealing with Rusty for over 14 years and he has ALWAYS gone over the top to solve any issues that arose......which in my experience has been very, very few.
There are a few people on this board that are running his wheels (and most of us have put them through the ringer in actaully road racing them) and I am sure that we all pretty much share the same opinion. Its the strongest wheel for the money and they look damn good on our cars.
The brake comment by Rick is an excellent point. The center on the 40 is different than that of the 45, and there may be some fitment issues depending on your combination of wheel and brake. Please post what you are going to be running so that we may be able to answer those questions before hand.
You can also call and talk to Rusty to ask him the same questions and get his input. I will however tell you, that he will give you a straight answer but will not elude to that you can fit more brake into the wheel. I was pretty much the first to fit a PBR 13" system into the 45 series wheel years back, but the 40 does have some limitations conerning this. There are some up close pictures of the PBR type 13" brakes in a 16" 45 wheel on my site, provided in the link below. As you will see, there isnt much room to fit any more in his wheels.
In closing, feed us some more info on what you tend to run and we will be able to give you the skinny on fitment concerning the 40.