diacetyl rest for ale yeast
What benefit does dropping an ale yeast down to 50 degrees have on the beer. Assuming that the beer has been fully attenuated and the yeast strain is a low diacetyl producer in the first place, why do it?
50 sounds rather low for a diacetyl rest. 15 to 18 deg C (whatever that is in deg F) is generally a more typical temperature. 50 sounds more like a temperature used for lagers towards the end of fermentation, when the temperature is allowed to increase - a sort of diacetyl rest. Not all lagers of course have this sort of rest.
If you are able to cool the beer down very rapidly, then a short rest may help the yeast to settle out without suffering too much shock, leading to cell damage, autolysis and off flavours / hazes etc.
Other than that.... But of course flavours do change over time, and at different temperatures. Perhaps the key is to taste the two beers, one fermented with a rest, one without. Make sure the bulk of the yeast is taken off as soon as possible to pervent autolysis though.
Have fun tasting. Cheers