the 9500 mobo has no problem with running when its not placed inside the case. I had a 7300 and 8600 running outside the case and on both died the onboard video and there were problems with the speaker/sound hardware as well. I later noticed that this is caused because the board has to be grounded to work correctly. It is grounded to the enclosure of the psu over the metal shielding inside the case (dont take it out of there! - i did on my 7300/8600 casemod and had to ground the mobo to the housing of the PSU using a wire, otherwise the mac refused to work). the 9500 maybe has none of these problems cause it has no onboard video.
BTW: no problem to take it apart in 5 minutes. but have you ever tried to fit a 68pin HD+ adapter in the case without breaking your fingers?