I like it.. I would think other's would like them as well.. There are a lot of 51 lover's out there for sure. I have seen the old Sheaffer pens fitted with a roller/ball point. I have a couple of the old Sheaffer CT pens and would like to fit one after I clean and buff the barrel.... I think I have about 40 or 50 vintage pens to restore... So, it won't be first on the list.
I certainly see some folks liking the idea. I have not seen these before, thanks for sharing.