Mamod william locomotives

[benchmark]

I have noticed that there are 2 Mamod William locos (william and william II ) both with slide valve engines does anyone have these and how do they perform outdoors?
Also, what is the basic differences between the 2 models?

Secondly as regards that unsightly regulator valve outside the cab on the boiler, are there any after market parts that one can buy to hide it? like a brass cover or something to that effect?

Thank you.