I will give my experience with lakes and ponds. First I do it primarily for fishing and wildlife habitat and jet or any other skiing has never been a consideration. If that is the primary consideration then I suppose the bigger the better. But I have not found that to be true for fish and fishing.
A 7-15 acre fishing lake is hard to beat. In fact, I doubt it can be beat. I've found that a lake this size is ideal for fish management. You can catch and fix problems much easier and efficiently with this size. Personally, I find that the larger the water the larger the problem when it comes to fish management. I fertilize the water and feed the fish, and that is just not practical on a 50 acre lake. The cost of fertilizer and feed alone would cost a fortune. And would produce no better fishing. Fish per acre and fish quality would probably be less since it would be much more difficult to manage.
The other consideration is that the lay of the land and the available watershed will do more to determine the practical size of a lake than the wishes of the owner. Any government agency or general contractor will look at this first and will use those geographical features to determine the dam location, the water line, acreage, etc.
In one way it can be compared to a house. A family could more comfortably live in a 3,000 foot house on one acre than a 10,000 square foot house on 10 acres. The routine maintenance alone would eat you up and you'd spend a disproportionate amount of time on this rather than actually using and enjoying it.
A fifty acre lake on four hundred acres is a lofty goal and with liberal resources it could be built and maintained. But don't be surprised if you soon find yourself needing a lot of equipment and sheds and barns to keep it in, and either hiring a full time maintenance man (or two), or plan on spending every waking hour taking care of it.
At the end of the year you'd find yourself catching more fish on one 15 acre lake than one that's 50 acres. Skiiing would be altogether different.
Good luck with your prokect and I hope it goes well.
