I tried growing seeds from fruits from a rootstock variety that had popped up, which I strongly believe was a rough lemon.
The seedling, which were grown to about 6 inches tall in containers were unable to survive a typical winter in Olympia, climate zone 8a, despite being on the deck only 5 feet from the house. It was a very vigorous grower though and did show some signs of mild cold tolerance, better than orange.
The fruits were nothing anyone would want to eat, pretty bitter and low quality flesh, but pleasantly fragrant.