1: parts are proprietary, so they will be expensive and rare.
You mean replacement parts (if something breaks), correct? I assume that is true with all new designs. Like you said, we'll have to see where that goes.
2: the design will be hard to adapt a drum for.
How so? I read somewhere that the part of the drum that fits in the magwell will need to be steel (not enough space for polymer). But other than that, I haven't heard any specific issues. Is steel (and/or steel/polymer together) more expensive than polymer? I guess it could be since polymer is molded.
3: "conversions" look to be difficult to do at home
I am not that familiar with the Saiga (I wanted one before the scare, but backed off until I can buy one for $600 or less, especially considering the conversions that they seem to need to just function), is that the system you are comparing this to in terms of the ease of conversions?
4: mags do not drop free, mitigating any advantage in reloading it may have over the Saiga.
Maybe they just don't have enough mass, or it takes a while to break them in. Maybe higher capacity ones (the only ones I'd really use) would. Plus, isn't one of the advantages of the magwell that it is easier to load? I am no expert, I just seem to remember hearing that.
I'm not trying to be a fanboy (don't own one, but want one), I'm just looking for clarification. I'm more of an AK guy anyway (though why do you have to pick sides?) since I own an AK and don't own an AR (unless you count the S&W MP 15-22 pistol, boy that is fun...but not really an AR).
In the end, I am probably just excited to see the market grow. Up until now the Saiga was the only game in town, and we saw the problems that happened at the beginning of the year when there was only one option (and there was the scare).
Like I said, my first obstacle is more money. Maybe when I have that solved, we'll know more.