I've always loved the 92 series, but never got around to actually owning one. Is the Compact L a good compact, or would I be better off with a Centurion or full size model?

Personal preference.
Rent one if youcan.
I owned a compact 92 20 years ago so I thought that's what I would want again. I rented a 92 and bought one team next day.

Personal preference.
Rent one if youcan.
I owned a compact 92 20 years ago so I thought that's what I would want again. I rented a 92 and bought one team next day.

The compact is an all around good size, it's what I'd choose to carry. The compact is similar to the G19 while the full size is similar to the G17.

Can you put the D spring in a compact?

 

Yes, except the spring housing is shorter than the full sized 92. This results in more spring tension and a higher trigger pull. The D spring is still a major improvement over the 20lb trigger spring. I'd like to try a 13lb spring.

I had one along with owning a full-size

It didn't shoot any different than the full-size one to me.  Shot just as good.  

It's not that "compact".  The shorter grip does make it easier to conceal, but it's roughly the same size as a Sig P229 or Glock 19 for example.  The shorter grip can also bite you in the hand when you're in a rush to reload it.  If you have meaty mitts, you can get some flesh caught between the bottom of the grip and the floorplate when you lock in another mag.  The flip side is you learn pretty quick from that to not get your hand in there  The longer mags fit and function fine, just sticking out the bottom a tad.

I'd suggest you handle both sizes of 92 and simply pick which you like best.  You can't go wrong with either one.

This.

I own both, the "compact" is only slightly smaller.

I prefer the compact slide on the full frame. I think Beretta calls them brigadiers or centurions, not positive on that one.