There's absolutely, positively NO good reason to use a hardmod over a soft mod. Generally people who reccomend hard mods are those who were impatiant, already have a chip installed and are trying to justify their expense.
Opening up a console, especially if you don't know what you are doing, ESPECIALLY if you don't have to is always a bad idea. The wii inparticular is a very tiny console with very small solder points. And while I am a huge fan of solderless solutions, the one's available for the wii don't have a solid mounting point (like a screw or something to screw it down with which is what was used on the classic xbox) so you could run into issues. Also the ribbon cables in the wii are quite fragile.
As for compatability issues, since the gamecube loaders were released there is NOTHING you can't do with a softmod. The audiofix and other issues are just a release or two away so don't be fooled into thinking there is better compatability with a hard mod. I've seen just as many "issues" posted about running game XXX with a chip than with a loader. 99 times out of 100 it's just a media issue.
So a hard mod only has one single thing going for it, namely faster read speeds. But I'll remind you that games aren't constantly loading huge amounts of data off the disc.... if they were then the game would slow to a crawl even at full read speed.
Also the thing about fmv's stuttering is flat out false. 90% of the time it's a result of the person burning to crappy media. The only legitimate slowdown I've seen is on Wario shake it, but that game is odd to say the least, using virtually uncompressed full 480p video.
