I vote yes...

You go for it girlfriend. Am betting you will be glad you did. if its the master...you probably wont have to go far to the bathroom, add a phone, a microwave and small frig....you'll never leave it. LOL.
I have often thought about sleeping in my LR and making my only BR into sewing area.

GO For IT!! ITS your House
 

Are you Crazy!! Do it If it was me I would have the walls down yesterday, it would be so lovely to have that space! You only live once so go for IT!! lol :)

Whatever floats your boat

Its your home, do what is convenient for you. You will be much happier!!!!

I say go for it. After all you are the one living there and you should be able to do what ever you want with the space you have.

I don't have a longarm but I have never used my master bedroom as a bedroom. I've never seen any point in using the largest bedroom for sleeping (I sleep in the smallest of three). Before I took up quilting, my master was a darkroom. Now it is a sewing room.

Go for it!

I also live alone and I took my family room and converted it into a sewing room.. It's big and roomy and holds about all of my sewing stuff which includes 3 machines and cutting tables and numerous sewing supplies, plus a tv. I still have a living room for watching tv and relaxing. My family room is in the back of my house so it isn't seen from the living room. I'm loving having it like this.

It's your house. If you want to turn the master bedroom into your sewing room, go for it. It's not going to
change anything about the size of the house. You will not be doing any construction. As a suggestion, use the
guest room as your bedroom. Move some of your dressers in there and let that become your bedroom.
You'll have more fun with the master bedroom as a sewing room than a bedroom that you never use.
Go for it.