No chance. I looked at everything I have in the mahogany family including sipo, sapele, African mahogany, America mahogany, Spanish cedar, etc. You can see them all on my mahogany anatomy page http://hobbithouseinc.com/personal/woodpics/_anatomy/diffuse porous/mahogany/_mahogany.htm
Bearings are bearings. If you don't have confidence in the ones you'd get from Grizzly all you have to do is read the numbers on the bearings and order them from somewhere else. I just replaced the bearings in my table saw motor and didn't try to get them from Ridgid, or the actual manufacturer of the motor who was so proud of their work they didn't put their name on it. If you want to retrofit a diy cool block setup then I should think all you need to do is get some aluminum square tubing and mount it to the part that the side bearings normal slide on. They'll only have one tapped hole in them but if you can add a second one or if there's enough sticking out then cutting a groove in the tubing for it to engage might work. Or you could look at how Matthias designed the guides on his saws and replace the whole thing.
I think the question has been well covered, but I'll throw in a bit more. To me, the first consideration when choosing is what kind of projects will it be used for? Large, small, wide, etc. I tend to be all over the place. I don't have a 4 1/2 (yet). I do have a Stanley 4, 3, and 2. I bought the two more just because it was a good deal and it's somewhat collectable. I use it a lot! It's a fantastic tool. Bigger isn't always better. The 3 and one of my 4s have pm-v11 blades. The 2 and my other 4 have original Stanley's. I have a LN 5 and 7 that I love and I'm sure the smoothers are amazing as well, but I don't feel like I've been held back at all by the older Stanley's, upgraded blades or original. I say that to say you could get a Stanley 3, 4 and 4 1/2 for now and when you see what your preferred size is, spring for the more expensive plane.