Is there still a reason to use old version?
There is always a reason to use the old version: it is the one that
is actually actively supported by Debian, provided with security
updates, etc.
If there’s a bug in the version in stable, then the version in stable
gets fixed. (If a backport already exists and is buggy, then of course
it gets fixed… or removed. But none exists here.)
I am got 3.1 from public Ondrej repository. The bugs doesn't exists anymore.
Ondrej’s repository is not Debian.
Debian backports are made from Debian, specifically from the next
stable (bullseye) or, before that is released, the “testing” di‐
stribution.
The current versions of the packages are:
buster: 3.0.3~dev20181093+2.1.7~dev20160128-1
testing: 3.0.4+2.1.7~dev20160128.orig-1
So a backport would give you 3.0.4, not 3.1… although there’s a
3.1 uploaded to Debian unstable that _might_ enter testing next
week (which would necessitate the backport to be updated).
If you really want to help with fixing the segfaults, then first
report them against the packages in stable, using reportbug, then
(if you can) check if they are fixed in the version in unstable.
Mind that the presence of *anything* from Ondrej’s repository
makes your system “not Debian” any more and can introduce more
spurious bugs; that is outside of normal support then.