What's the current price of 4 position trigger group ?
There is one up for sale and it seems like he is asking a lot but I have no clue.
Also how does Colt bypass or overcome the forged in stops at the safe and full auto positions ?
I believe for the 3 burst position the selector points straight down.

Or is this just a novelty that wears off quickly ?

When selling an M16 years ago I chose to sell off a three burst version and kept the full auto one.

They seem to run anywhere from $1000-$1500 these days.  The Colt version requires milling the stops down. Maybe some custom ways around that, not sure.
I went with the DPMS version a few years ago. No milling required with their design. I really like having the option of 3RB or FA. I'm sure some will call it a novelty, but I enjoy it.

John

Thanks. The version for sale is a Colt.
I'm not milling down stops of this expensive of a gun.

I'll look for a DPMS version then.

Oh it 100% is.

Idk anybody who actually prefers the burst position, and it isn't needed anyway once you're experienced. (Meaning you can accomplish any burst simply with trigger control, consistently).

Besides, none of the burst mechanisms available for the M16 family are auto-indexing, and they all negatively affect your semi-auto trigger pull by having each different slot of the burst cam modify the trigger pull every time you fire semi-auto (since the burst cam is constantly engaged).

HK's burst mechanisms are more mechanically complicated, but their complexity overcomes the two above-mentioned design pitfalls.
I own a bunch of select-fire weapons, and the only 2 models I've intentionally put a burst trigger group on are the MP5 and G36 (and the SG551-2 simply happened to include burst) however all additionally feature a full auto position. I don't actually use the burst position (except the 2rd burst for certain range drills which require exactly 2 rounds) but I usually have novices use burst when I'm instructing them initially because they lack trigger control.

That said, here's a video of a 9-year-old firing my MP5 (which was his first time firing anything full auto) and this was back when I just had a SEF trigger group with no burst limiter. We just told him to keep replicating his initial 3rd burst, and he had no trouble whatsoever repeating this consistently so it's not a difficult skill to develop. Anyway, that's why I don't generally recommend them.

Novelty IMO. I put more priority on having a two stage match trigger in semi auto which is why I use a Giessele SSF