There are some issues with configuration files and environment variables, and from what I have heard V4 and V5 do not live happily next to each other.
As an alternative I have a dual boot system. Linux Mint 17 with KiCad 4.0.7 and Debian Buster with KiCad V5.
Both distributions share the same /home partition, so finding files is not such an issue for me.
A few days ago I did an sudo apt-get dist-upgrade, and the KiCad version it installed on Buster is:
Version: 5.0.0-rc3+dfsg1-2, release build
libcurl/7.60.0 OpenSSL/1.1.0h zlib/1.2.11 libidn2/2.0.4 libpsl/0.20.2 (+libidn2/2.0.4) libssh2/1.8.0 nghttp2/1.32.0 librtmp/2.3
Platform: Linux 4.16.0-2-amd64 x86_64, 64 bit, Little endian, wxGTK
wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 2.24
OpenCASCADE Community Edition: 6.9.1
Compiler: GCC 7.3.0 with C++ ABI 1011