I put maybe 1k rounds through a new, used police trade in 92fs in the last couple months. I replaced the trigger return spring with the tcu immediately and have really enjoyed shooting my beretta after 10 years off from them. Im not sure why but I felt like the trigger got "harder"  all of a sudden so I replaced it with the original trigger return spring and its night and day difference.

The double action pull is only slightly improved but the single action is really nice now. I guess if it breaks Ive got another original and the wolff tcu to replace it with.

I don't believe the TCU was designed with good trigger pull in mind. The geometry seems to indicate only strength and reliability and not so much lighter trigger pulls.  Or at least that's what my experiences with the TCU tells me.  It has its place on a duty gun as I feel you'd be really hard pressed to ever break one however.

This is discussed on the Beretta Forum all the time. There also seems to be some natural variation in those spring kits.

I tried that INS spring setup once years ago. I had a D spring in my Beretta - the trigger unit put the pull back up to the stock weight. I took it back out and sold it.

The trigger return springs are made of thicker wire than they were many, many years ago. So, the old suggestion of changing the factory trigger spring every 5k is probably overkill now. But, I'd rather deal with changing it than the added weight of that spring unit