As far as sentimental; well if I had a choice of not using my dads gun to defend myself at 03:00 am or keeping an intruder from harming my family? Well I will sure miss that gun!
The thing is for most of us -- probably almost all of us -- no gun we were sentimentally attached to would also be the gun we'd rank as the gun we'd achieved the highest mastery with. We don't have to choose to use Dad's old gun, and in fact that would probably be really the least likely choice in any case!
Grandpa's short-chambered Model 12 is probably not the gun you've shot the most 25/25 rounds of skeet with.
Great Grandma's S&W hand ejector that she used back in 1923 to face down a couple of hold-up men in her father's dry good's store is probably not your best USPSA/IDPA gun or the one you take to defensive training classes.
The old Winchester your dad passed down to you before he died is probably not your go-to hunting or defensive or competition rifle.
And so forth. For most of us, we've built up our skills and found proficiency and mastery with fairly modern guns we picked because they were well enough developed/advanced to give us the benefit of modern features and engineering, and were cheap enough for us to purchase at the time.
The OP's conundrum is a little different in that he's imbued sentimental value, too great to risk losing, on modern guns that he himself used to build and demonstrate his skills. Whereas most of us would look at that Glock or SIG as the gun we've "ridden hard and put away wet" through all those 10s of 1000s of rounds of practice and competition -- and strictly a tool like a magazine or holster to be replaced when worn out or damaged or somehow lost -- the OP sees an heirloom in the making.
So it is a bit of a special case.