I can share my experiences with CE Metal Can Caps since 2005.
My results are mixed, using the CE Metal Can Caps, especially on some Amps.
So I stopped using them in Amps that operate the first Section of the Cap close to the rated DC voltage.
These CE caps seem to work fine in applications that don't suffer from AC Transformer Voltage Boost.
I call this common condition Vintage Amp Hypertension.
Un-regulated Tube Amp Power Supplies, with primaries wound to an older standard of 115V or 117V, are prime candidates for some TLC and Norvasc 5mg.
Hammond makes a series of new Power Transformers that offers dual primaries 117/125 VAC.
This I have found to work very well, especially in Cathode Bias designs where the Tube Current Draw permanently aggravated by boosted Secondary Voltages, not to mention the AC filaments that I have measured at 7 to 7.3 VAC on my old Stromberg AR-411 Amps.
Using a Variac is a temporary solution as there is really nothing better than a Power Transformer that is wound to work well with the AC line voltages we have today, I would call these "The Millennial Series".
All of the Amps that I build, are designed to account for this difference. And when my friends ask me to work on their older Vintage Amps, I always offer to replace the Power Transformer to optimize the Amp to be plug-n-play in any modern AC Mains. Its always better to operate an amp at or slightly under the steady state voltages that the factory publishes. You would be surprised by the Voltage and Current measurements otherwise.
But the best solution is to replace these older Power Transformers with modern units that are wound with sensible primaries or have dual primaries.
I have experimented with the Dynaco Reissue Plate and Filament Transformers, with some success.
My Dynaco MK3 Clones work fine, and these are Fixed Bias so I can turn the Tube Current down to compensate, although this also tends to boost the DC voltages as the load on the Power Supply decreases.
My ST-35 is one amp that I needs replacement of the Dynaclone Power Transformer,
Even using the ST-35 Bias Boardm, the amp operates mostly out of range, and it loves to gobble EL-84's for Breakfast, Lunch and Dinner.
The only tubes that stand up to this abuse are the Russian variants that operate up to 450V on the plates.
But to my ears, they lose the EL84 sweet magic, we all love, they have a colder, dryer presentation, some may even prefer it as accurate.
When I operate my ST-35 with a Variac, I can see the whole amp relax, and the filaments operate as intended, not as surrogate night-lights in the dark