I would agree with that, I just finished my TK, it's an FX kit and I weigh 220lbs, I know there is no way I could fit in the smaller armors. At this time I have the FX bucket (I got my unbuilt kit from a squad mate for an amazing price so I'll start with the FX bucket lol.) but I am already looking toward something to replace that. I am now searching for another set of armor to get started on my TD so I'll be searching for some used FX or an FX lite kit and maybe a TE2 bucket, since I do have a large melon.
Good luck on your build, there are plenty of helpful people on here to keep you going.