Hi,
here's my test install using GitLab:

Project page:
https://git.xet7.org/Secretchronicles

TSC repo:
https://git.xet7.org/Secretchronicles/TSC

main-website repo:
https://git.xet7.org/Secretchronicles/main-website

Settingseditor repo:
https://git.xet7.org/Secretchronicles/Settingseditor

I think that because I have not added other users, imported issues look like they were created by me.
Adding other users and reimporting could probably fix this.

GitLab is Ruby on Rails app, and runs these embedded software in it's subdirectories:
- gitlab-workhorse
- logrotate
- postgresql
- redis
- sidekiq
- unicorn

HTTPS to Nginx is added using this free https://letsencrypt.org project, and these instructions:
https://webnugget.de/setting-up-gitlab-with-free-ssl-certs-from-lets-encrypt-on-ubuntu-14-04/

GitLab:
- uses more RAM and CPU resources than Gogs
- has GitHub issue import etc features
- currently I have it installed on 1GB RAM server with nothing else running, memory usage:

# free -m
             total       used       free     shared    buffers     cached
Mem:           994        930         63         22          3         43
-/+ buffers/cache:        883        110
Swap:         2047        156       1891


GitLab hardware requirements:
https://github.com/gitlabhq/gitlabhq/blob/master/doc/install/requirements.md

Gogs:
- uses less resources
- does import repos from GitHub
- I don't know have they yet implemented importing issues from GitHub

BR,
xet7