Conumdrum's right. Reservoirs don't provide a performance gain. Go with what you want, whether it's something fancy like my Liquid Fusion reservoirs (those glowy spiral things in my post) or something basic. It's all personal taste.
Comparing the Switch 810 to the 800D isn't very fair to be honest. The 800D is nearly twice the price of the Switch 810. NZXT probably had to cut some corners in order to keep the price of the Switch 810 more budget friendly, so unfortunately the build quality is going to suffer. I know there are some that have issues with NZXT using so much plastic in that case, but to me it's still a great looking, affordable watercooling case.
Just so you are aware,
Corsair has announced the 900D (not yet available though), retailing at about $350 USD. I'm not sure what your budget is, or even if you'll need that much cooling capacity, but in case you haven't heard of it I just wanted to let you know.
An all aluminum case tends to run higher than steel/plastic cases, but you get what you pay for. It's a very subjective topic, really. Your personal prefs, watercooling needs and budget will all play in the case you choose. I don't really feel comfortable giving you a definitive answer.
Also, you may want to consider starting your own thread. Not that I mind helping you, but I did intend this thread to be a build thread (regardless of how few updates it's been getting
). You'll probably get a better range of responses as well from other forum members that might pass up reading your questions in here.