Well, I kind of already gave a reason to stay at 3.2U... It was because all of the other Wii's I have around the country have that Menu version and they all work 100% flawlessly.
I am not a Wii hacking expert but in everything else that I have hacked in my life, (DirecTV, Dish, Xbox, iPhone, PS1, PS2, Tivo and various computer games....) it has always been beneficial to stay at the lowest stable version of firmware. Only exception being if you really need something from those later firmwares (which I have not found a need for in the Wii and I have ~200 games already working flawlessly to support that claim).
Do you have a really good reason to upgrade to 4.1 when a wii is currently at 3.2, 3.3, etc? If so, I haven't seen that posted anywhere?
Just my .02.
Side Note, from the guide, I did just realize there was a never version of cIOS38, thanks!