I own HK 223 A3 and here in Europe it was 2.5k slightly used. 3.2k new but unavailable, nowdays 3.4k.
My friend has an LMT.
Both very nice rifles. The LMT does not yet have a lot through it but runs well with flow through suppressor.
My HK has 15k+ on it and while the first CL barrel was amazing out to 12k, it started to degrade after that.
Have not changed any parts except the gas port actual gas port to fit the almost completely (legacy) suppressed shooting I do.
MY HK is more precise and is a bit heavier, mostly due to the big barrel which heats up quite a bit slower than the LMT. The LMT was quite bad with accuracy but it improved a lot when it had the suppressor on. The HK is maybe a teeny tiny bit more precise with suppressor on, but my other suppressor did worsen it slightly.
Both are reliable. Apart from the problems I had with my gassing from the first winter I had it (I ended up reducing buffer weight but it later might have been the gas port that was carbon locked to misbehave) I have not had a single malfunction and did last winter shoot the gun at -11F succesfully without suppressor.
The LMT so far seems to have one problem. Whereas I bought the HK with the 12" handguard, the LMT came with one too. I replaced mine with 14" so I could work with the stuff I have on the rifle but my buddy is doomed to have no space to properly install his to a pig mount or have adequate space in the rail for good hand placement which really eats up the positive sides the rifle has.
So get yours with enough handguard to begin with.
I do plan on buying LMT MARS in 6.5CM since HK does not make one and it looks like it has no faults in it. The HK over here is 4.4k for G28 and the LMT is 4.9k but is on sale for 4k at the moment.
HK
LMT