I have two buddies with tandem IK's and they paddle them solo and loaded. No problems either way.
I have a outfitter solo and just got the tandem. the solo paddles great unloaded and spins and handles runs on the ARK in BV just great. I personally have not paddled the tandem outfitter solo but have paddled it tandem and it does great.
Others with more IK experience than me can give you their experiences. I think you probably have two of the higher end IK's both construction and what I will call "paddle ability".
I think you determine just how well your IK's paddle, solo, tandem and loaded. All of us Buzz fans can give you all sorts of opinions. The real life answer is you are the answer and only you can determine just how well your IK's perform.
So get out on the water and learn to paddle each of your IK's and gain the skill set needed to make them perform at the level the boats are designed.
I been following your posts and it seems like you are in the South East. I grew up in that area, now in Oklahoma (midway between quality Rocky Mt and SE runs). For what it is worth, get out on the Nanty. One awesome river to train on. Easy to do multiple runs in one day or weekend. Take your boats out and run them down the Nanty. Get some instruction from NOC. Bottom line while the Buzz is a great place for opinions, you are the factor that determines how your IK's perform.
Be safe, have fun and paddle all you can!!!!