After getting a Medium Solid AF from Hookah John, I figured I should update this thread with answers to my own questions for anybody else thinking about getting one. I agree mostly with what bradedup said.
1. Is the heart a solid piece with ports, open chamber, or open chamber with cover plate for ports?
It's actually none of the above. The heart itself is hollow, not solid. It's formed in the shape of a solid heart unlike those with an open chamber and a cover plate.
2. Is the hose port wide bored? How well does a Razan hose tip fit into it? (I've read it's pretty small so the fit of the Razan is a concern)
The hose port bore is about 3/8" wide but it is constricted inside the hose adapter which has a smaller inner diameter of slightly under 1/4", about the same diameter of the purge port and that of Myas.
A Razan fits well enough in the hose adapter that there are no performance issues. It's better to put the grommet/gasket (gromsket!) on the hose tip and then into the hose adapter.
3. How is the purge compared to a KM?
As mentioned above, the diameter of the purge port is just under 1/4" but the purge valve opening is a measly 1/16" hole. The cap has 4 1/16" holes on it's side. I do not agree that it purges better or equal to a KM. The good news is that the hole can be enlargened.
4. Is the draw slightly restrictive or is it more like a KM?
It's draw is pretty open but I cannot answer this properly without a side to side comparison with a KM.
5. Have they fixed the short down tube issue?
The down tube terminates ~2" above the bottom of the vase so it's not really a problem. I'm not impressed with the vase and wish it was bigger as it isn't very stable.
There were some holes in the brazing of the stem tube at the top bowl end and around the hose port on the bottom of the heart. I rebrazed them using a butane torch, flux, and lead-free silver solder (SnAgCu) and cleaned it up with some grinding/filing. I also cleaned up the sloppy brazing around the purge and hose adapters as well as I could and removed the crooked donut thing that was on the bottom of the down tube.
The weight of the stem comes from the brass pieces that make up the decorative elements of the stem itself. From what I can tell, not all of them are solid but I wouldn't be able to tell for sure without disassembling it.
The purge port on mine came with a very small internal leak in it somewhere. When one end is plugged and I blow in the other, air comes out of the top portion of the bottom gold plated section of the stem. I could see some rough machining on the inside of the purge tube but it would be very difficult (read: nightmare) trying to get at it to repair. I decided to just enlarging the purge port hole to 3/16" and the purge cap holes to 3/32". It purges much better now and it doesn't seem to leak during normal use because I couldn't detect it in a soap water leak test I did when I was smoking and purging last night.
The bowl tip part of the hookah is removable and pretty rough inside. I smoothened it out but I had to remove quite a bit of material to get all the rough spots out. This caused some thin areas where there are grooves on the outside. One in particular was very thin so I reinforced it with some solder from the inside.
I probably won't ever use the hose and bowl that came with it as they aren't very good. John was kind enough to give me a different set of tongs instead of the crappy one that AF includes (I didn't even have to ask!).
I was thinking about converting the stem into a 2pc so the downtube portion can be removed for easier cleaning but the hollow heart is probably going to keep me from attempting it. I'll reconsider if I want to lengthen the stem after gettting a larger vase. For those of you with the large AF, could you measure the inside diameter of the base opening?
This post turned out much much longer than I had planned.