I love the sound of my Jolida 102b. It is powering Athena S3/P3 speaker/subs, which are very efficient. I appreciate the warmth of a tube amp. It's a great sounding amp for a reasonable price. No issues with tube biasing. It's quick and you don't need to do it often at all.
All tubes will drift and pull more or less plate current over time. All amps should be biased at least once a year. And tubes should be tested at that time to see how close they are to each other * power tubes * preamp tubes left to right should also be matched to each other including each pair of sections. Also bias should never be done with out knowing plate voltage
More often than not this can vary depending on the tube that is in the socket how the transformer is wound and they are all slightly different producing more or less line voltage, the circuit it self resistors caps drift from amp to amp not to mention line voltage. Making it impossible for a manufacture to say set it to this number and it will be perfect.
So biasing a tube amp just based on plate current with out knowing plate voltage is pretty useless. IMO you should never go above 70 % plate dissipation unless you have a class A amp. And again you cant do that with out knowing plate voltage and current draw. For some tube amps a bias meter like the Weber bias rite can be used or the Compu bias providing that your tubes are compatible with these devices. These testers give you plate voltage and current draw. This is a cool app I have on my iphone that helps me with the math.
https://itunes.apple.com/us/app/tube-bias-calculator/id557429027?mt=8 This may not have some of the tubes you will be using but it should have most of them.
And remember a amp that is not properly biased will sound like ass.
Chris