First I want to start off with the bottom line for most buyers; pricing! - Right now as I write this the 800D demands $299.99 at Newegg while the 700D demands $259.99 at Newegg. So off the top you can save $40, not too bad. I honestly can't say that based solely on price the 700D is a better chassis. Design is essentially the same on both chassis' if we look past the hard drives orientation, hot swappable bays and the lack of a window. The elegance of the Obsidian series could carry the rather large chassis as an addition to any living room in the simpler 700D form, where the 800D's window may not be a needed feature in that instance, so by all means go with what fits your needs.
Issues are very limited in either version and specifically with the 700D there is even less to go wrong. One thing I need to address that didn't happen to me personally, but I have seen various reports of in reviews and in various forums, the plastic cover for the CPU back plate access has weak hinge points and is easily susceptible to breaking. Two close personal friends I recommended the chassis to both received their chassis with this problem. I can completely see how it is possible with two tiny bits of plastic being the only thing holding them in place aside from the latch; rough shipping or an odd angle could easily make it happen. With quite some time using the 800D and now looking at the 700D, I can't find any other faults.
I have had all sorts of air coolers inside my chassis, including the D-14 from Noctua and there are no issues with size. Running SLI and air cooling all the way, I have to say interior temperatures are very good with the three zoned setup. Each can handle their job and I am surprised of the amount of heat that can be removed in the main motherboard section. Running an i7 860 over 4GHz and dual GTX 275's, temperatures have never been an issue.
That leaves you with the decision of what is $40 worth to you. The 700D is a bit easier to assemble the PC inside of, but I personally prefer the window and the hot swappable bays of my 800D. Either way, you are going to get one of the best chassis designs I have seen. While the chassis could offer some more tool-less features for the price, I have never seen anyone refer to the Corsair cases in any other manner than it takes the fun out of modding. For those without the time, or the abilities to run a Dremel successfully, you won't go wrong buying an Obsidian Series chassis in either form. I do however wish for those looking to buy one that Corsair and Newegg would make a bigger difference in the pricing. $40 isn't enough to sway my decision in the end. If the pricing was closer to the $225 range I would definitely say go for the 700D, but I will leave it to you to decide which is best for you.
PRICING: You can find products similar to this one for sale below.
United States: Find other tech and computer products like this over at Amazon's website.
Australia: Find other tech and computer products like this over at PLE Computer's website.
Canada: Find other tech and computer products like this over at Amazon Canada's website.