some camera brands 'rate' their cameras by the number of cycles a shutter should take; 100,000 or 150,000. How do you know the 'reliability' of a welder?
I believe the answer to your question, can be found in the many reviews, and Youtube presentations about the various brands and types you may be interested in.
Another thing to think about, regarding 'reliability/longevity', is what is your long term vision for what you will be needing it for? And how you will be using your welder?
If it is just for this hobby of bike building, and not much else, then more than likely any mid-priced welder will probably work. Though some of the cheap ones can very well work for a very long time, depending on how you use it and take care of it.
I answered that question by doing research, as I am suggesting. I listened to all the opinions, looked online for reviews, and watched YouTube videos for each welder brand I was interested in. Once I 'learned' about welders, I was in a much better position knowledge-wise, to make an informed decision, as to which one I wanted.
Below is the 'Deciding Factors' of how I chose my current welder. (Written and posted back in 2013)
I'm as pleased with my choice today, as I was the day it arrived from Northern Tool.
As it has turned out the 25 amp lower voltage has come in real handy for my use.
And the 5 position selector has proven to be quite effective.
I've been using a 10 lb spool of .030 ER70S-6 MIG solid wire I got from HF.
And from day one, I've had absolutely no problems with it.
Then there is getting the gauges and a tank. I am using a set of gauges,
also from HF, and haven't had any problems that I'm aware of.
The tank I found online, is a 55 cf tank, that I paid around $85. I think. I can't find the receipt at the moment.
It was a reconditioned tank, that had a new valve and a fresh hydrostatic test date, which was good for 10 years.
This is important because any reputable welding supply store will not fill your tank if the HYDROSTATIC test date is over 10 years old. They checked mine today, and read the old date, but I let them know there was a newer date.
I had mine refilled for $37. Seems like each time I go, (about every six months) the price goes up by $3 or $5
I'm not sure if I have answered your question, but the more insight you have about choosing your welder, and associated equipment, the better you will be able to answer your own question........and hope that your answer is right.