Level 50 1/2 Duo - what to do

I just finished Chapter 3 last night. I was directed to Ilum but have also picked up the Makeb quests. Should I skip Ilum and go ahead with Makeb instead?

I had 90+ Planetary Comms when I finished and nearly upgraded my armor/mobs with stuff from the Correlia Modification Vendor...until I noticed the Makeb Vendor right beside selling kick arse Modifications for a little more. Now my duo is kitted out with 25 Purple armor/mods.

Also what about HK-51?
Is it possible as a Duo?
I read you need a level 15+ Imperial char which I don't have. But I am playing on an Australian server which has a pretty low population as most people have transferred to the US ahead of the server merges. There were 50 people online last night in prime time and I was 2 out of 3 level 50's. I could probably walk in to Imperial space and win the war :)

Illum is just daily quests. It gives good xp until about level 52. The only reason to go to Illum would be to make credits. Makeb is the expansion planet and will start chapter 4 for you.

Thanks Riiker. I had a quick look at Ilum over the weekend but it just looked more of the same and I was a bit weary after 50 levels. I skipped to Makeb and got a new boost to keep going.
Makeb is great, there is only one or two side quests to an area which is good as I was ignoring most of those anyway since level 25ish. The story keeps moving along and the world looks great. I am not even noticing the levels flow in as I go this this content :)