:|:
:QBB:
Correct, the DSL/TSL had cheap and flimsy PCB mounted pots but the daughterboard with the pots was somewhat stabilized by the screws. The new JVM took things to a new level of cheapness for an expensive amp. The answer is going to be obvious - Marshall crammed a lot of technology into an expensive amp and they had to control costs.
Since 99% of the people who buy guitar amps will never leave their bedroom with them it makes sense to cut the costs and deal with the warranty issues. The pro level musicians that do tour with this mass produced gear can afford to have multiple backups on hand so the reliability issue isn't a deal breaker for them as long as it's not constantly breaking.
Smaller manufacturers can't deal with the repairs and don't have an acceptable failure rate so they build things to much higher quality standards, but their time and materials causes the cost to rise. It's a trade-off.
Time will tell how the JVM holds up to heavy gig use. I'll be looking for a cheap used one when the honeymoon era is over, I really like the concept and the clips I've heard so far.