Ask yourself, are you really going to swap barrels back and forth? If so, tighten that belt and drop the cash for a factory barrel. Another reason is you won't have any down time while waiting for the barrel to come back (unless you timed your Form 1 and barrel to come back around the same time).
I am planning to send mine to Buhler Ballistics since they quoted me $125 plus shipping with a 2-3 weeks turnaround time. I heard really good things about them from many people so far. They will reattach and time your muzzle device while opening your factory gas port to 1.9mm. I already bought the PMM 1.9mm gas port in preparation of my form 1 coming back so I can send them my barrel and the gas port without them having to mess around with the factory one. My check for my Form 1 was cashed a few days ago so I might wait two months and send my barrel in so it can come back to me around the same time as my Form 1 (based on the estimation that it will take them 3ish months). If the barrel comes back before my Form 1, I guess I'll let one of my friends on my trust hold onto the barrel while the rest of the rifle is at my house.
PMM, which are pretty well reviewed, but has a 2+ month waiting time and is longer.