You make good points, I can't argue that. The thing is though, that you seem to be taking the game section by section and not as a whole. I don't think the cop is necessarily a wash if one cop dies because they can investigate the same person more than once. So if there is a switch, it is known that their reads can be reliable from that point onward. If there are more VT added, this gives a better chance that Cops survive to claim. Alternatively, everyone can say who they are going to investigate that night and leave their peeks then next day. This way, it provides cover for cops in the case that one dies. if the game goes long enough, a cop can peek the same person again to see if they have switched yet (I am not married to the amount of VT in this game). Also, there is a different between mason and Cop in this context because mason deals with collaborative information while Cope deals with singular information.In post 8849, mith wrote:"If there is not a switching mechanic, it is just too town sided" is not equivalent to "it is a good idea to have a switching mechanic".
If you get to day 3 with both Cops alive, and you haven't already lynched scum, that means there is only one Townie left. It's certainly possible that the Cops will be able to piece together whether they have been switched or not (investigating the same player on different nights would do it),ifthere is no counterclaim, but if you are in this situation obviously one of the scum will claim Cop and muddy the results further.
If you don't get to day 3 with both Cops alive, as Jason points out there is not enough information for the remaining Cop to go on.
When you say "investigate your strongest reads", what you seem to be implying is that you should rely on those reads to determine what your sanity is, rather than relying on your results to determine what your target's alignment is. Which you should be doing anyway, so what is the Cop role adding?
[edit]Also, if what you're after is "Cops should try to stay alive so they can solve the game day 3", just make that their role:
2 Masons
5 Townies
1 Mafia Rolecop
1 Mafia Goon
If both Masons are alive when there are 5 players remaining, town wins.
[/edit]
Investigating your strongest reads tells the cop how certain he can be of his reads primarily, not necessarily that his checks will be correct. I admit that Cops primary role in this game does not really function as an alignment checker, but more as a confidence meter. If the Cop wants, they can check the same person every night until there is a switch and then he can then depend on his alignment checks.
Masons work differently in many ways in the setup you suggest as replacement. For one, the collaborative component is something that is not found in the setup I have put forth. With masons, you can do things like coded messages that you can predetermine before hand which is not something you can do with a sane and insane cop. Another difference is that if Cop plays the part of what alignment a player is as a single player with a clear result either way. This is different than mason in that masons can disagree on reads or agree on them or a mix of both. I would also argue that masons in a game like this could be much more exponential in the info Town has to work with as the game goes on rather than linear. The reason for this is that masons have an exponential amount of info coming in as the game goes on based on the fact that they can clear each other and this in combination with the fact that as time progresses the masons can get closer to agreeing on reads thereby making synergy a factor not to be ignored. With this said, two masons pushing the same player(s) is not something you get with a sane and insane cop since Scum can CC.
IDK if I have argued my point well enough. I have a hard time explaining what my actual thoughts are sometimes. There is prolly more I can say about this given structure to work with.