I've attempted to attach a photo (I hope it works!) showing the difference between the two types of vacuum pumps. Looking at the old design, you can see how the bearings could potentially escape if the pump failed...
The 'old' one in the photo was taken from the car when it had 199,000 miles on it. It still looked (and worked) perfectly fine, but I thought I'd change it just to be safe after reading about the potential problems it can cause if it breaks.
I found the new Pierburg vacuum pump online for $211.33 with free shipping. Although the vacuum pump gasket is available as a separately orderable item, there's already one included with the pump (so you don't need to order one - I wasted $4.72!!
).