We did some statistics about the 14 million good abc triples below 10^18 taken from Bart de Smith site.
This was examining just the top of the iceberg, since the interesting triples grow very likely well above 10^18.
We were interested in $\#\{a :a \le c^\alpha\}$$\#\{(a,b,c) :a \le c^\alpha\}$ for real $\alpha$, as $a,b,c$ are taken from the good triples, assuming $a < b$.
Here are the numbers:
alpha , #a<=c^alpha in percents
0 (a=1) 0.31
1/4 2.38
1/2 11.75
3/4 38.59
9/10 70.34
The arithmetic mean of $\log{a}/\log{c}$ is 75.894%, which is very close to $3/4$.
We did the same computation for the 234 (give or take few) high quality triples (quality > 1.4) and the data is:
0 4.27
1/4 16.24
1/2 35.47
3/4 68.38
9/10 91.03
The arithmetic mean of $\log{a}/\log{c}$ is 58%.
Can we get some heuristic arguments about the distribution of good abc triples?