Yeah it certainly doesn't look like it would contribute much to the overall polycount.
akt_m's Yamato is the nicer looking one but, according to the wiki, it has about 2,000 more polys (assuming that that figure of 26,000 polys applies just to the ship itself) than what a juggernaut-type ship would be expected to have (24k polys, but they can have more). royloo's one is closer to a cruiser/freighter in terms of polys, according to the guide in the wiki.
The limit on the number of rotating subsystems is a bit of a downer; I take it that it means we can't have all those turrets rotating? I thought turrets were a separate class to subsystems (*waves noob flag*). I have visions of this thing trying to shoot down scores of planes attacking from multiple directions with its AAA batteries. Changing some of them to static single-part turrets would avoid hitting the limit, right? Except that would mean we'd lose the coolness factor of rotating turrets somewhat (I'm not really keen on single-part turrets but anyway I don't want to whine too much about it, they're probably a necessary compromise in this engine).