Alpha pots are higher quality pots. Just because they're higher quality doesn't mean you don't get a few duds or have a issue every now and again, but it will happen less often. It's the same with anything you buy. If you buy high end tubes you still have a chance of a dud tube or having it last then it should, the key is your chance of that happening should theoretically be lower then buying cheap tubes. You can apply this to anything. The problem is that if you spend more on something that should be good quality but it has a higher instance of problems and duds. Personally I've been using alphas from tayda for close to 8yrs and never had a dud. Side note the ones from blms do not come with pot condoms, so if you were to factor into the price buying them your going to spend about $0.50 a pot.
The knobs are the same as the ones tayda sells, and it's a question of if they'll will fit the pots or not. Btw, I do like blms and have order a bunch form them, and you will get a better deal if you buy enough knobs from him, plus shipping is cheap a chips.