Ok Kil, now I'm really gonna pick your brain. I agree on the drag/fight time and am not opposed to a long rod to jig w/ per se, just didn't want to buy any longer than is necessary.
I've seen you write about casting being a big part of your jigging. What does that entail. I've casted Tady style jigs to tuna (both heavies and surface iron), but are you casting japanese style jig? What's the technique?
For some unknown reason, I have more bites when I jig under the boat than when my jigs drift away. To maintain my light jigs more in 90 degree in current, the best way is to cast upcurrent.
Of course, casting away from others' lines helps not to tangle with other lines.
By casting far away from the boat, you can cover in differnt depth.
Sometimes we have tuna close to top early in the morning and I had pretty good success by casting away.
It is a challenge to catch yellowfin tuna among so many blackfin in Gulf Coast. The first thing I want to try when I go down there is the casting method. You don't need to be a rocket scientist to figure out where you fish when most yellowin usually stay on top and blackfin are thick in deep at oil rigs.

When tuna are on top they usually stay outskirt of lights of a boat and you need to cast to reach them.
Our tuna jigging fishermen on the East Coast are heavily influenced by cod jigging which has been done for generations. Casting is always an important part of cod jigging and I've never seen a good cod jig fishermen who can not cast. The most popular length of cod jigging rod is 8' on party boats.
Most of my tuna jigging rods ( I use them for cod jigging too) are 8'. I experimented a 6'6" Japanese rod and Calstar 700H/700XH purposely this year. I found that the shorter rods are more convenient when I fish on a small private boats, but I still prefer the 8' rods when fishing on a big party boat. As I said before, you can fight with long 8' rod effectively when using the rail. However, you have more advantage of using shorter rods if you want to fight on harness. You can fight a 8' or longer rod on harness whether it is a spinning rod or conventional rod, but there is a trememdous difference using 6' rod and 8' rod when using a harness.
I see many Gulf Coast fishermen got to know Japanese style jigging systems and use them. But I foresee they will recognize the merit of long jigging rod eventually. We need both depending on fishing situations.