For those features, under $4K is going to be tough. You probably don't need acoustic, unless your speakers have to be behind the screen (acoustic tab-tension screens are fairly uncommon, though you can get them). If you do get something acoustic, a black backing would probably be needed (I think this is one of the reasons a lot of companies don't want to do acoustic electric screens). With ambient light, you definitely want a gray or high-contrast material, or your picture will appear washed-out.
Hanging a screen in front of a fireplace is probably okay, but if you extend the screen with a fire going, or while it's still hot, you will damage the screen. To avoid accidents, I don't recommend putting it anywhere near a heat source.
If you decide you can do the $4k screens after all, I'd go with Severtson. For lower cost, I do usually like Silver Ticket better, but as you noticed, their gray electrics currently appear to be sold out, plus their tab-tensions only come in white. You could contact them and see if they have any other options, though. Sometimes they'll have something that might work for you.
Hanging a screen in front of a fireplace is probably okay, but if you extend the screen with a fire going, or while it's still hot, you will damage the screen. To avoid accidents, I don't recommend putting it anywhere near a heat source.
If you decide you can do the $4k screens after all, I'd go with Severtson. For lower cost, I do usually like Silver Ticket better, but as you noticed, their gray electrics currently appear to be sold out, plus their tab-tensions only come in white. You could contact them and see if they have any other options, though. Sometimes they'll have something that might work for you.