I can't speak for any of the newer units which probably are even better in this regard, but the older units that used several crystals in both the reference and offset stages would probably require a touch up or even replacement after many years as crystals do drift with age, so for an old unit, it might be worth it, For a new unit, especially today when much of that conversion is now locked to the reference, I severely doubt it in a new unit. Crystals are made in low profile, hermetically sealed units for large batch smt contruscted units and highly unlikely to drift short term even with long distance transport. As the above poster said, these crystals are not in an oven or TCXO but out in the open with no temperature compensation, so temperature does affect them as well, so setting them at room temperature is going to change once in your car on a chilly morning or night. These radios were never intended to have voice color tolerance under temperature extremes like a marine or commercial SSB unit.
The there is the so-called tune. No manufacturer is going to sell you a radio that's not been optimally tuned. You might see some better numbers by a golden screwdriver guy at a truck stop shop, but there can be many reasons. The company may stagger tune using a sweep generator so the tuning may be broad enough to be wider band either to keep spec across the 40 or anticipates you modding the frequency range. That extra bit of performance may come at the cost of the top and bottom or result in spurious signals that are reduced within spec by the staggering, so the output you see on a meter is not the output on carrier only. The may also set drive and power controls to keep from approaching the maximum disappation rating of the devices. That insignificant power will not translate to a difference in S readings on the other side, but will shorten the life of the radio. Same goes for audio and limiter mods. They make the radio look better on a meter, but cause distortion and bleed over. Again, you're also probably pushing many devices out of their safe area.
So they do this performance tune and you now get a crappy sounding radio and one soon to fail along with bragging rights. Who is going to support the radio during the warranty? Chances are mr golden screwdriver will sell you a "performance enhanced" radio, but upon failure or problem, tells you to return the radio to the factory or warranty repair station for service which will probably decline it due to the mods in warranty. You don't have many of these guys doing these mods capable of working on SMT boards from the photos and videos I see of their benches. I don't see hot air or IR stations on their benches or any rework tools that have been used since the 90's, so it's improbable that they can do a component level repair. If they could, they may not have a source for parts even as a distributor.
Companies are not in business to sell you an underperforming product that would tarnish their reputation that needs enhancement after the sale. Those limiters are there for a reason to keep you in spec and legal. If you're that hell bent on ruining a good radio, wait till after the warranty before you let one of these butchers screw with the radio. I'm absolutely appalled by what I see these clowns do on youtube videos. Had I ever worked on a radio using the sledgehammer techniques and crude rework tools they do, I'd have been fired or taken around back and put out of my misery. Like I've said before, these guys are for the most part out for a quick buck. If they really had the skills to work on these radios competently, you can be sure they would be working somewhere else for a lot moe unless they have lines of suckers waiting in line to be ripped off and have other income coming from sales of other profitable items. Minor increases of power and so-called swing mods and limiter removals do nothing more then decrease you inteligibility and stress your radio beyond ratings. You're not getting someting for nothing. Companies are under a lot of pressure to sell you a radio with very thin margins to maintain competiveness, so the components they choose are going to be the minimum needed for the 20% intermittent duty cycle intended. Raising the average power output even in SSB by speech processing or audio limiting may indeed be pushing the ratings of the device's average disappation.
When the radio goes dead, is that extra $50 bucks of bragging rights worth it when they tell you to suck wind on warranty?