I know this topic has been brought up before. I, personally, prefer to have the whole gamut of wetsuits. 6/5 and everything in between. I do my deal hunting and never pay full price.
My current spring suit is dead, after 5+ years of service. I had a 2mm full suit short-sleeve. Great suit for a lot of conditions, but a lot of times in summer, the full leg felt excessively warm.
How about short johns? Never had one. I have this idea of combining a short john with my 2mm long sleeve top for chilly summer dawn patrols. Then being able to shed to the top when the sun starts to cook.
Combining different suits is generally a bad idea but I like the idea of having versatility for summer conditions.