Hello,
I use IN6 (Neoden) and generally can recommend it. In the beginning have some problems, one heater wasn't good, after some time mostly spend misunderstanding due to language barrier they sent me spare heater. I order directly from China , price about 2k +shipping. If You have light boards (not heavy copper and massive components) You can put and bake boards continually. Large boards with lot of copper (ground plane) need some distance between each other because the heaters in last (hottest) zone are not powerful enough (my opinion, which Neoden don't take into account). Anyway, it can withstand 80 boards per day. It have carbon filter on exhaust, but if you want clean (and cold) air in working environment you must conduct the air outside. I haven't other reflow oven , so I can't compare results with competitors.