Tell you what I know, from what I have gleaned the commercial grade longbows £4K, over time had various tubes fitted , some been milled to fit, others with different connections etc, all clever stuff by my standards, cannot recall if it’s the inverted tube or non inverted which suits the longbow.
Then there were higher grade tubes fitted with higher price tag above commercial grade, gen3 etc.
Have basic commercial grade longbow which is fine, but no telling how long any tube will last, but in theory many many hours. Another couple of members on here shared their experiences and gave me some good advice on retube but decided for the money to run it into the ground, so to speak.
If day scope fails badly no fix, so just a lottery really am afraid to say, but others know far more than me on the technical joys of the longbow nv unit and it’s merits.
For certain you will get a nice one for under £2500 , after that it’s fingers crossed.