I had a 10mm i1991-1993 and traded it for a .40cal. The reason why I did this is .40cals were being loaded to perform as well as factory 10mm loads, and 10mm ammo cost more back then.
Plus I never could find any selection of 10mm.
I loved handloads through the 10mm, but had to depend on a friend to keep me stocked up......
Just an absolute different pistol with handloads......... The 10mm should be to the .40S&W what the .22mag is to the .22LR, but sadly to say it wasn't with factory loads, may be today, but not then.
With this being said, you can find .45 ammo anywhere, in all kinds of flavors, with reasonable prices. I like the avaibility of ammo. .22, 9mm, .45, .223, .308 type stuff you know......
Don't get me wrong though the 10mm is a TEN MOTHA MOTHA and they are awsome! Mine was a stainless SW 1006, looking back on it, Should of Kept it and bought a .40 later.
All this Being Said....... beg her to let you buy both