My main on one of my accounts is fast approaching the ability to run L4's with a good R&D corp.
I will be fleeting him with a R&D char on another account to grind standings. This R&D char has the skills for good datacore farning, so I want this R&D char to move to a 5.0 standing quickly.

What is the fastest progression: L3 Security or L4 security missions?
Naturally, L4's give a larger bump/mission, but given the speed I can complete L3's, I am not sure which is better.

I'm guessing you'd be better off sticking with L3s if you can't blitz L4s yet and your only goal is to grind standings.

Sorry, I was not clear. The ratting char is quite capable in L4's, but was fast approaching the 5.0 standings with the particular corp to run L4's.

It'll help if you tell us if you have an expensive fitted missioning ship, and where you currently are running with it.

Depends on what corp it is and if you plan to grind standings for more R&D corps in same faction. If the corp has a storyline agent/mission agent in same system it's faster to blitz for storyline missions as some of them give a huge corp increase i.e. either blitz lvl 3 combat missions or use a fast hauler in a distribution mission hub. It's was dumbed down after the removal of agent quality, so it can be done in a couple of hours now.

Thanks.
I will have to investigate the probability of getting storylines with the same corp.
I do know that the L3's have been giving me non-corp related storylines, and have been passing on them.
Maybe the L4's have a better storyline agent nearby.

Thanks. I fly an x-type/officer fit Mach.
When my char is online I will look you up so we can fleet together and we can grind missions together.

It is much easier to find me in a crowded system if we are fleeted together.
Maybe you could bring along some friends in Catalysts and Tornado's so we can run these missions faster.

Much thanks for your support.