The push your luck aspect was cool at first but then became tedious. I always had to count how many decay symbols were left in my deck so I could decide if odds were good to push my luck. When you do go bust and spoil your turn let’s just say it sucks. With so few plays I’m not sure of a good strategy for the push your luck part. Is it never take it? Rarely take it only it when there is a really good card you might gain or take it any time odds are in your favor?
I view the push your luck aspect as more of expanding your options. Let's say, I have 3 mana with 3 decay showing and the only thing I can buy is the Fertile Soil for 2, but there's a couple of great 4 mana cards out there. Or, like your example, the card I want won't fit in my field, but if I had one more mana I could get x card instead. In both cases, pushing your luck could be worth it.
There's also times where it doesn't seem smart. For example, you might need to push your luck more than once to get a good card you want (too risky) or you already have stored mana from your last bust and you won't get the consolation mana for busting this time, or you have blue shield points in your field that you risk losing from spoiling. . .
I really like the push your luck aspect. I think it makes your decisions a little more interesting.