I'd take the kettle you have and try smoking on it a couple times. Whether you get a cajun bandit conversion, their stacker kit, a smoke-ez or whatever - i'd try it before you go buy two more.
I have a OTG 22.5 with a smokenator setup - it works extremely well, but it requires a bit of attention for temp. I'm happy with it for shorter cooks (ribs/chicken/etc) but don't have the patience to go the distance with a brisket or shoulder on it.
That said, i'm in the same situation as you are, and I'm saving up for a WSM.
The UDS option is tempting, but I appreciate the ability to break the WSM down and store easier. And my wife doesn't appreciate the charm of the "U" in UDS.
Cat Daddy's BBQ : 22.5 WSM / Weber OTG 22.5 Cajun Bandit / Smokey Joe Gold