Pet Aura IOs on a Crab Spider

Has anyone experimented with using the Pet Set Unique Aura IOs on a Crab Spider? Did it make a noticeable difference in the survivability of the pets?

On the one hand slotting all four and adding a +20% resistance/+10% defense to all my pets sounds potentially very useful. On the other hand I can definitely find other uses for those slots .

Would love to, but don't have the slots. Also, I don't think the radius on them is too huge so I imagine I'll find myself out of range from pets quite a bit considering they like to do their own thing most of the time.

Ah, for some reason I was thinking it was 20... yeah, 40 would be nice... still I'm already having a hard time trying to get rid of some stuff to make room for a couple of PvP IOs. Besides, my pet powers are already slotted for perma-spawn.

I've never had that many slots to spare. I think I have ONE, in a pet on one of my huntsman builds, but never all of them.
I have a pair on a Thugs/Dark that I no longer play, but I've never done any testing to confirm just how much they help or not.

I'm looking at switching a couple of sets of 5 red fortune for 3 lotg's and a regular IO end reduction, freeing up 2 slots that I am considering using for the 2 pet defence IOs - this would give an extra 10% defence on top of the ~20% they get from double maneuvers, which would likely do their survivability a fair bit of good.

On the other hand I also have the pet build-up IO sitting around in storage, and 2 of my 3 pets are somewhat underslotted for damage, so even if I did decide I'd use the slots for my pets and not something else entirely I'm not sure I'd go with the defence IOs... ah decisions decisions!