I didn't do the mod because in my line of work I often see companies who sell two products that use the same parts... one will be "certified" as faster. This simply means that said chip was tested and found to run stable at a higher speed and remain within spec, while the other chip was not. I saw in the eevblog that they are doing some over-clocking? Perhaps this is the case. They test each scope after it is made and the ones that pass within spec when over-clocked are badged as the 100Mhz model, the one that didn't pass for some reason is badged as the 50Mhz.
Sure you can always attempt to make the slower version run as the faster version, in fact I see many people do this. The result is usually the product fails prematurely or gives odd behavior. Sometimes this is reversible, sometimes it is not. Often, it takes a while before you start seeing symptoms... so testing a product right away and saying it worked is premature.
I purchased a 50Mhz scope and got a good deal on it. I might as well get my money out of it before I risk trying to mod it.
Just my two cents :>