What are the downsides to modding your Wii? What are the risks?
The downsides? Apart from the very small risk of breaking your Wii drive board with dodgy soldering or blowing a fuse, there's the risk that future games will introduce new anti-chip protection that will prevent new games - even originals - from running. They've already pulled that one out with the Error 001 stuff. Most chips are updateable though, and if the chip isn't then replacing a solderless chip with a different one is extremely easy. A crappy soldering job could also lead to instability. Some chips also have issues with inching/ejecting in certain circumstances, although I don't think that's a problem on older Wiis.
On the other hand, a modchip gives you more flexibility in fixing issues affecting the software (i.e. bricks) by being able to boot special discs (homebrew discs at System Menu 3.2 and under, and autoboot Twilight Princess discs on any version.)
Also, as soon as you open your Wii your warranty is officially out the window - whether that's true in a practical sense is another matter, but since yours is a launch system I assume it's got no warranty left anyway.
The benefits are that you generally have 100% compatibility with backups and are better able to fix software bricks in the unlikely event that they arise. The software solutions are getting pretty good at the moment, although that could very easily change in the future. Chips are far more resilient against attempts to defeat them than backup loader software.
QUOTEWhich solderless one is considered best? I got my Wii on the day it came out, if that helps any.