Point of Reference for the Original Poster...
The Wilson, and I believe, to some degree the S&A magwell/MSH's will require some minor fitting to work. They tend to come slightly oversized, and if you simply install one on a gun that HAS had any flaring to the bottom of the grip, you will get an angled step where the inside of the grip runs straight out, then angles out, and hits the add-on funnel.
By blending, it INCREASES the opening on the magwell, and makes the part appear to be a part of the gun. Since most guns have slight differences in the grip frame/magwell opening between makes, this IS an issue, cosmetically.
The stainless Mag Funnel's aren't easy to work, and require some good files... I know, I screwed up my Wilson, and just left it, and will start fresh with a new one, and fit it better, or have a pro do it.
One other point... Without the 'relief work' I did on the rear of mine, the mags would not seat fully, or drop free...
If I get a chance, I may post a pic, and show what a non-fitted magwell looks like...
I will say that I prefer the MSH/Funnels over the slip-on ones, or weld-on ones... While they may not be readily removed, they can be removed, and if the gun doubles for Carry, and Comp, can be useful.
On my dedicated carry gun, a LWT Commander, I would agree with Dane, in that they defeat the purpose, and with proper training, or practice, don't offer much of an advantage.
If you did notice Larry's example, he angled the bottom outside edge of the Mag Funnel. I really liked the appearance of this, but what made the difference is the style Stock set that was used (and that Larry didn't pick). The flush bottom (covered pin) style made the stocks appear to extend down, and that angle on the mag funnel made them appear like the bottom edge of a normal set of stocks. I prefer my MSH pin UNcovered, but that small detail was appreciated, at least by me.