Our experience with LMB and SMB reflects what has been said above.
We bought the place with 1/4 ac pond in 2009. Former owner said all sorts of fish were in it including LMB, YP, GC which we've seen, and BG, CC, BCP which we did not catch nor see.
LMB were fry, 3 to 4" fish and a few adults in 10 to 14" class. No fish in between 4" and 10". YP were most common at 6 to 8" and a few 10". Incredibly high crawfish population with them visible at all times. No vegetation; mud bottom.
Pond is irrigation water fed from Dolores River, a trout stream. Water is available from April to October, then shut off. Very little surface runoff in this arid high country of sw Colorado. Pond is 9 feet deep maximum then loses depth to about 5 feet throughout the winter until the irrigation water returns in late April.
I've been culling LMB as the years go by, trying to get fewer mouths to feed.
As the reservoir on the Dolores has SMB, it's been no surprise that a few SMB have come down through the irrigation pipe over the years. These are little guys-4" fish. I added 18 SMB in the 7 to 10" range, a few at a time, over the first 3 years of our pond ownership.
Although there appear to be no LMB large enough to eat the adult smallies, these larger SMB, while visible and catchable (always C & R), have dwindled or disappeared. Last summer I only caught 1 SMB; previous years I would see and catch several.
Our home overlooks the pond ( I know, it's time that I post pictures-my bad) from 75 feet away. We have observed only 3 dead fish in the 5 years we've been here, all LMB, 2 small, and 1 (16")with eyes bigger than his stomach, who choked to death on a 9" YP! Once in a while a GBH visits; no mink or otters, so really no predation on the bigger fish.
Pond is now loaded with Elodea. I clear fishing paths at times.
All this rambling is to say the SMB that we've had seem to disappear over time. The LMB prolly are pushing them out of the better foraging areas and reducing their efficiency at finding food. Nearly every LMB I clean has crawfish in its gut. There is only a fledgling population of BG, introduced last summer. I'm hoping for a spawn this next summer. Water temps are not warm enough for BG to spawn repeatedly throughout the season. We successfully over summer RBT and BRNT.
Whew! Too long of a post, but then I like to talk about ponds.
Here's an unrelated question for all. We purportedly have 200+ ponds in this county-Montezuma. Now one pond owner I've ever met has heard of Pond Boss. I've never read a post on this forum from someone else living in this area. What mechanisms exist to spread the word around here about the advantages of managing one's pond with help from Pond Boss? People don't seem to get that with a bit of management, their ponds could suit them a lot better than they do now.
