Great feedback, thanks! I chose the regiment mainly for their extended rapid fire range, but you're right; it seems like the Steel Legion playstyle is centered a lot around jumping in and out of transports? what sort of strategies do you find they lend themselves well to?
The extended rapid fire range is very helpful. The regimental doctrine is centered around putting those transports forward, dismounting in like a 17 inch range, rapid firing, and then mounting back up. I find that Plasma guns are particularly effective in the troops squads as they benefit as well.
Some tactics involve running two wave style tactics, something your original list actually had. This would be running a transport or two up with hard hitting, essentially suicide troops that force the enemy to address them, while the second wave follows behind either securing objectives, or positioning themselves so that when the first wave is killed, the second wave is now in rapid fire range. It is all about maintaining that 17 inch rapid fire death zone. This is a modified version f what is called the "distraction carnafex" tactic.
Another tactic is strategically using the land based transport vehicles to block line of sight, and cover the relatively few infantry models you have.
As far as what land based transports to use, I am still getting feedback. My go to is the chimera for fluff reasons, and because of the slightly higher armor and transport capacity. Also because it has a lot of firepower for a transport. However, Taurox are also very useful as they can go slightly faster, and cheaper at the cost of less armor, weapons, and transport capacity. If you are running a lot of normal ten man squads without commanders, those could be a better option.
If you like the flyers though, you may still want to check out the Elysian Drop Troops. They have their own orders like Hold the Line to ignore casualties when taking Morale tests, and Move and Fire meaning instead of being able to shoot after Advancing, the unit simply treats all its weapons as having the Assault type, so you could move normally (or Aerial Drop) and fire Heavy weapons with no
BS penalty. Perhaps that style may be closer to what you want to do.