I should clarify, put the stock solution in sealed bottles and only dilute for use.
Oh, yes. It is super stable and never let me down. Even with the very high contrast I'd sometimes encounter in Afghanistan, it handles highlights very gracefully. I cannot think of a better all round standard developer and at 1+2 and 1+2 is is in no way soft.
I also started mixing it (1+3) with Rodinal 1+100 for some films and, combined, it is the best developer I have ever used for slow films, bar none. Does amazing things with D100, APX100, Foma 100... takes a few tests to sort out development times, but boy what a combo! None of the brittleness of rodinal negs when heavily enlarged (very crystalline grain) and moire bite than Xtol alone. I found that very fine grains really benefitted from teh extra acutance that the Rodinal brought to the party. Two developers = three options and both will be around for ages. If Xtol disappears you can always make your own Mytol and Foma makes a Rodinal equivalent. This gives you redundancy.