I can use my parents for the NBC thing, but I just wonder how much of this is convenience, like flipping back and forth from the O's and The Golf Channel is extremely easy with Satellite/Cable, using push a button. How fast do these internet based options do this? It seems a bit cumbersome. (first world problems, i get it)
Depends on exactly how you do it...
If you have 1 source feeding your TV, then it comes down to how rapidly that source changes channels. Various options here, so not just 1 std answer.
If you have, say, 2 sources feeding your TV, then it's however fast your TV's remote can change from one hdmi input to another one... the actual change will be virtually instant, it comes down to how many button presses your TV remote requires to do it...
If you wanna use mlb.tv to get around the MASN problem, and if you live in O's territory and therefore need a VPN, then you're gonna need some kind of computer to feed that... and old slow laptop will do... or even a netbook that somebody is throwing away... or maybe an android tablet... so, that would be one of your sources anyway, with maybe a Roku as the source for everything else...
Also, TIVO makes a box called a Roamio that works with online sources and OTA local channels... this would allow you to record OTA (if you get the right Roamio, which is one of the cheaper ones)... it also has a search function that allows you to tell it want you want, and it will find it among whatever online and OTA sources you get... (the trick with TIVO is to get a lifetime subscription, which normally costs too much, but there are legit ways to get it cheaper than the std price...)