I’m in the same boat as Mike… I have an A model with a McClung armrest and an F model without an armrest. To tell the truth, I don’t notice it either way. (I suppose if I took it off the A and installed it on the F, then I would notice). The nice thing is that there is no drilling or modifications to your mandolin. If you try one and don’t like it, simply take it off and post it on Mandolin Cafe or even here on the forum. They sell easy and you won’t lose a whole lot. I think you’ll like it though, most people do. Some people claim that the mandolin sounds better with an arm rest because it allows the top to resonate better. I really don’t see that myself, but I’m not a sound freek. I’m 51, just glad I can hear.
What kind of mandolin would you be putting it on?