On 30L I can get 2-3 short CPU only sessions or one really long one. Never have benched I7 or GPUs on LN2 though so not really sure how long it would last for that.
As far as a pot goes, the KP bullet shaped pot is the Dragon (Evo?) which had multiple revs up to 2.4 IIRC. It is indeed an excellent value as they can usually be found for only a few dollars more than the Koolance tube is new and completely destroys is in LN2 performance. The only challenge for the Dragon may be finding a 1366 mount for it.
Personally though, I'd probably drop the extra cash for the F1EE if you can swing it. THe way I look at it is the difference in price between a good tube and the best is fairly insignificant relative to the amount of hardware it will cool during its lifetime.
For dewars, Ebay can be an excellent source. I found my 30L in almost perfect condition for under $300 including shipping. If you are patient you can almost always find a deal .
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