I always found my MF1's ran very hot and high heat is not generally electronics' friend. So a few years ago I got a bunch of very thin washers and by using them equally (a pair at every point) internally under the standoffs at the bottom of the case and again between the case and lid top at the screws, I created a very thin air gap, about 1mm in width at the case top. It still gets warm but it's not as hot as it used to be. The only cosmetic issue is having to omit the front top center screw because the top is now offset by 1 mm. The other issue is that this gap allows dust and dirt to get in, but unless you're working in a jungle it's not a serious consideration.
This way I feel more comfortable knowing that the components aren't overheating, but in fact I have no evidence if this makes a difference or not. Logic says yes, but I have no empirical data other than not having had any issues with these boxes so far. In the end what it did accomplish for sure is make me feel a whole lot better about it. :-)
Now of course, the caveat: unless you are comfortable taking apart boxes like this, I don't suggest you do it yourself. But it's quite simple and any tech-minded person could do it quite easily as long as they're very careful with the components in the box.
FYI...
PC1 = HDSPe PCIe: DF-ADI-8 DS / HDSPe PCIe: MF2
MBP = HDSPe Expresscard: MF1