Upgrading or not to HQ 9 has been discussed several times here. You know the advantages of going to 9:
And the disadvantages:
Events require more EP and more time to complete key missions;
Daily Objectives become longer and more annoying
High number of medals/high base score will push you into matchmaking of Prestige rivals.
I have a Rebel base HQ 9 "Watchman", that was just like yours, created to play Events only. It had 6 Level 1 turrets, which was my mistake to build in addition to 2 turrets, and even though I didn't build any traps, it threw a high base score. The second mistake was never having dumped medals, and the third and fatal mistake was upgrading to HQ 9 with 35k medals at the time Prestige was released, which threw me straight into the big Prestiges matchmaking which are the same as I face with my Rebel Prestige maxed out.
Dumping medals to 25k was no good, and I was too lazy to drop more medals, so I abandoned this base for PVP and I am upgrading it to be a full HQ 9 only to play squad wars.
The secret of happiness in the SWC I already said is called medal dumping. If you want an authentic mini, build no more than two turrets and no traps. Instead of building more turrets that will add each one 25 to your base score, upgrade the 2 turrets you already have (an upgrade level adds only 5 to your base score).
The better is don't upgrade any turrets, if you have high level GR and Prestige buffed units in your SC -- you don't need more than that to win in PvP and HD. I have an Imperial mini HQ 8 "Lord Avlis" with 29k medals that still finds HQ 7 and HQ 8 because it has only 2 level 1 turrets and no traps. I get Bronzium in every HD and win all my defenses if the rival doesn't use Trucks, Trains or Buffed Jets.
In my opinion, stay at HQ 8 and enjoy Events, if you already have a Prestige to feed your mini. Go up to HQ 9 if you have the patience to drop medals whenever rivals are 1 or 2 levels above you. Depending on the level of your 6 turrets, they can push you into the matchmaking of strong Prestiges along with a high number of medals.
I have no patience to drop medals, and just for a testing, I created a third Imperial base "mkenobi II" with 2 Level 1 turrets, no traps, no shields, no tradeports, 1 level 1 refinary/market. It's HQ 8 now and I use it only to feed my main Prestige with Snipers for defense, Jumps for attack and other units for deploy troops objectives. And with less than 1k medals all rivals are Dev bases with 350-750k resources and 4-32k CB, and some Live also mini bases like mine.
SWC Windows survivor.
Imperial HQ 11 & Rebel HQ 11 on vacation.