Light 45ACP Load VS Standard/Mid 9mm Load

So I told my buddy the other day I was considering getting a 1911 in 9mm.

He says save your money and just load lighter 45ACP "cheater loads" and

get a lighter recoil spring.

4gr of Clays behind a 200gr bullet is what he used before and he said it's

pretty much like a 9mm. That way I can keep using my Kimber for just about

all shooting applications: Major Ltd 10 and Single Stack USPSA, and light

loads for static steel and knockdown steel, Pro Am type matches.

My original plan was the 9mm 1911 would be for steel competitions and the

45ACP for USPSA/IPSC. But if I follow his suggestion I could shoot it all with

one gun which I'd actually kinda prefer. I wish they had a 9mm slide that'd work for

a 45ACP.

So for those of you who load both would you say a light 45ACP load is comparable

to some degree to 9mm? I could answer the question myself but I won't be near

my press for a while and kinda hesitant to underload 45ACP.