People keep saying gravelpit is good for spectators but I very much dispute this.
Firstly, all the teams of equal'ish skill always opt to use the same strategy. And it seems on RED it's devolved into 2 strats, Ironman (which rarely gets used) and the standard B hold with 1 offclass.
If gpit is the real "test" of strategies then watching the same strat being executed time and time again is not really a good way of showcasing that.
Gpit is a test of team chemistry and timing, why teams do well and why teams do badly even though they're running the same strategy is something that comes down to timing and comms. To convey that in a stream is very hard, especially using only 1st person POVs and no mumble comms. In fact, it's also really hard to convey with those tools. As a comp player myself I know when it comes down to troubleshooting why we are doing badly on gpit, a cursory glance at the demos won't reveal it like the other 5cp maps, we have to go deeper, watching the same demo from different POVs, recording comms and listening back and getting opinions from higher div players. It's not something that can be communicated in a stream and I think it actually alienates new to comp players.
Secondly I would argue that gpit is actually horrible to new spectators. There's too much nuanced rules of thumbs that are being employed for new to comp players to know why teams do something. Case in point is the give up A approach RED always takes, it just doesn't make sense to new players and it also doesn't make sense as a map. Why play a make where 1/3 of it is basically never used and is always a formality?
The above is from the perspective of a spectator, specifically leaning towards someone with little to no comp experience. I think it's a very dangerous road to walk down to start playing maps that are not in the official pool as it would just alienate the pub community more. People can wrap their heads around 5cp, KOTH, but if we start introducing maps like Standin as has been suggested then it's going to be very hard to convey that in a stream. Hell, it was hard for me to pickup and play.