Been using X's for over 25 years.
Like all bullets, they have a velocity window they work best in. Unlike most cup and core slugs, it's pretty much impossible to cause one to blow up due to high velocity impacts. The actually work better the faster they are driven.
It is possible to shoot very long range (Low impact velocity), and have them pencil right thru without expanding.
For hunting at "Normal" range (Impact velocity is more than 2000fps. Which equates to 450-500 yards for majority of sporting cartridges), they are without peer.
If you want to shoot beyond 500 yards, maybe a softer slug is a better choice.
In last 10 years, I have not seen the need to clean bore of all jacket material before shooting an X. And if you must clean all the time with X slugs, you have a rough bore that will foul with jacketed bullets as well.
The original designs from pre 2000 did foul (And showed erratic accuracy in otherwise accurate rifles). They fixed both of these claimed issues 15-20 years ago.
I am in near 100% agreement with all you said. The only place where I would disagree is the blanket statement regarding Barnes bullets not opening below 2000'/sec.
Not all that long ago,,,,,in the past year,,,, I had a lengthy discussion about this with a Barnes tech info specialist.
The velocity at which they will open is now specific bullet dependent. Some will open just fine as low as 1600'/sec.
The tech specialist gave me a list of examples of many bullets that will open well way below 2000'/sec.
For me however it is a moot point for two reasons. One, I have never taken a game animal past 400 yards. And two, within the first year after I stopped using lead core bullets my blood lead level dropped from 5.5 micrograms of lead/deciliter to just under 3 micrograms.
By current health standards 3 micrograms is not considered high, but those standards reflect the influence of the vey powerful heavy metal industry. Especially for unborn to 6 years old group 3 micrograms is deep into the proven harmful zone
The negative health effects of lead are always there but often times hidden from easy scrutiny at the sub symptomatic level both in human consumers and scavengers.
Unfortunately, the powerful heavy metal industry, has thrown so much doubt, denial and confusion into this issue that we as hunters are needlessly and bitterly divided. The heavy metal industry has been engaged in the same type of denial campaign that the tabacco industry was doing for decades,
Barnes has a toll free number and will tell you anything you need to know about the range at which they will open.
Last thought, those Votex factory loads have proven to be very accurate for me in three different chamberings,