Ever gone from seperates to an integrated?

Geoff, I upgraded from seperates to an integrated. Pretty much for exactly the reasons you explained. KISS (Keep It Simple Stupid). I owned a Luxman pre and 2 Luxman power amps (circa 1978) that I ran bridged. I am presently using a YBA Passion Integre.

I will NEVER look back.

I will admit that going from 300 wpc to 100 wpc is noticable. But, let my use a different analogy.....

A well tuned 454 big block Chevelle will run a quarter mile in the 13 second bracket. So will a Mazda RX-7.

It's just a different ride.

Yes, I have; and back to separates.
The Air Tight ATM-1 is a stereo amp that has 2 inputs and a switch between them, but no active preamp stage...It was fairly low-powered at 35w, but beat head-to-head a combo of Krell monoblocks/Krell preamp when driving a fairly efficient speaker(Genesis APM-1). At the time, I was carrying my ATM-1 around to dealers trying to mate speakers with it. You should have seen the faces on the salestaff after the little tube amp crushed the Krell. They were almost speechless.
Short signal paths can be a benefit, but it's tough to generalize that one approach is best. Think it will vary piece-by-piece. If you're into vinyl, I'd argue that most separate phono stages will trounce the ones in most preamps...

Yes I have and I will never go back to the stereo amps, mono-blocks amps and pre-amps. At my time in my life over 60 I decided that my stereo was to large and complex so it was down-sized .Less power cords ,less interconnects, less electricity ,less to look at. I bought a Gryphon 2100 Callisto and was finally exposed to how my music should sound. The Gryphon is not inexpensive but it delivers the music as it was recorded in my opinion. The dynamics and the low level detail is unbelievable . The remote is also a convince.

I went from separates (Audiolab 2000C plus (2) Hafler 9500's) which I still use in another system, to a Jadis Orchestra Reference. Absolutely a killer integrated amplifier! My wife, as well as some of my audiophile friends have given very high marks on the exchange, and, I agree. Even though I went markedly down in power, I don't miss the loss of power at all. In fact, the Jadis sounds even more in control! (No hard rock, though.) Hihgly recommend the audition. Happy listening.

Definitely downgrade in sound from Sep to Int.