just a small update.
I had the new clock running for about two weeks (new clock uses a temperature compensated crystal), calculated out how much slower it was running, and sped it up ( changing the clocks speed in its software). I have now recorded almost two full weeks after being calibrated, since the calibration, its kept absolutely perfect time. its really appears to be perfect as compared to the reference time that i'm using. I find that amazing.
so I thought that my Sven was really good, it seems to me, its likely going to be around +6 sec / year. but TXCO clock might go less then +2 sec/year. I'll keep recording its time difference and see.
Answer to the question, is the TXCO worth the extra cost.. I think so. I think very accurate clocks are more interesting then less accurate clocks... with that said.. I think Sven is plenty accurate enough for almost anyone and my ITS1 clock seems to be just as accurate, which makes sense, as its similar. I record the same thing for my QTC clock, but I suspect its very similar to the Sven clock. I really appreciate that you can speed up or slow down the clocks via a setting in its software.
I will attach a graph of the new clock when I remember to get it from work

(Every morning when I start work, I record the time difference from the reference time on the internet).