Only if you prefer the ease of use with folding bellows as compared to bag bellows.
Bag bellows can be prone to sag in a way that partially blocks some of the light from the lens. Depending on the type and number of movements used, it may not always be obvious from just a cursory look if part of the bag is in the light path or not.
They're also fussier to get to store correctly in a camera, such as the Sinar P2, where the front and rear standards latch together for transport. Since you haven't indicated what type of 4X5 monorail camera you have, we have no way of knowing if yours is or isn't such a camera. Of course if you have two sets of bellows with you in the field, at least one of them will be detached from the camera during transport.