Steven,
Although I'm not a carp angler I do do a lot of spodding for bream and tench. I've not found any need for a spod rod, I'm more than happy to use standard 1.5 - 2.5 tc rods for spodding. Granted I don't use a big spod I use the gardner pocket rocket, which in my experience is the most accurate one I've ever used. I fill the spod with water (no bait) and cast beyond the marker float, then wind back until the spod is just in front of the marker.
Clip the line up and your ready to go, feather the line through the air and you have a very accurate method of baiting at distance.
Of course if your going to use a spod the size of a washing up liquid bottle then you need a specialist rod with a shock leader. But I sometimes think its the biggest, heaviest is best mentality rearing its head and I am more than happy putting up to a gallon of bait in using the method described above.
Oh, and plug the spod with a small amount of very dry mixed groundfeed to stop the particles falling down your neck when you cast !
Good luck