Most likely it will make no difference but powerline like wireless print magic numbers. The powerline guys almost admit it when they sell a device than can do 200 or 500m and they only put a 10/100 ethernet port on it.
In your case its going to be a very hard call. Most the testing sites show the 200m powerline units running at about 50m so if you happen to have poor wiring in your house it may get even less. The 500m units generally get in the 80m range so it give you a little more leeway. If you had asked about 30m or 60m then it is a much easier question but with 50m it hard to say if it is going to be worth the money.