I do not own a Stanwell Featherweight, but I too have looked over them a few times. I have heard the same thing as you that the stain rubs off but from what I have heard this only happens for a short bit while it is new and eventually that stops. I have handled these personally at a local B&M and attempted to rub stain off the pipe... nothing came off. Perhaps it needed to be warm for this to happen. Who knows. I don't know what that says for the pipe itself if both of us have heard this...... It would not however be a deal breaker for me as after hearing this as well I still look on them from time to time thinking of pulling the trigger.
Stanwell seems to have a pretty good reputation though with many people putting them above Savinelli, of course there are also many people putting Sav over Stan so really that means nothing......
Either way it is a cheaper pipe overall in their line up and I suppose a few flaws as listed is to be expected. For the price, if you're generally interested in it, understand that the pipe is indeed a small one, and are willing to deal with some stain rub for the first few pipes I say go for it. I bet that little pipe would smoke a coin of Escudo wonderfully.
I'm a straight pipe kind of guy so the 239 shape in the Tan finish is the one that interests me the most. Followed by the 202 in Tan as well.
It may be worth mentioning that all the incidents of stain rub that I have heard of all come from the Red stain'd pipes.
Just me .02 for whatever it's worth.