The Vandys are great, but do need a bit of room to breath. I am in the process of upgrading from Vandy 1Cs. Although my room is larger than yours, placement restrictions meant the logical upgrade to 2Ce Sig IIs would not work. I am currently auditioning a pair of Ohm Walsh 2000 speakers. These are too big for your room & expensive, but the Micro Walsh Tall (MWT) model should be ideal for your situation. They come with a 120 day in-home trial, www.ohmspeakers.com. Like the Vandys, the Ohm Walsh series seeks to minimize the impact of the cabinet on the sound. There were many things I found similar between the Vandys and the Ohms, like the big, open soundstage, and freedom from box resonances. Of course, there are plenty of differences, the most obvious being the Ohm's lack of a narrow sweet spot for listening that is a characteristic of Vandersteen speakers. I don't think the MWTs will go quite as deep as the 2Cs, but from what owners are saying, the bass output and extension is satisfying overall.
The problem with downsizing your speakers is, of course, getting the lowest octave and a half in your price range. It might not be possible without spending more or adding a subwoofer (or speakers with built-in powered subs).
The problem with downsizing your speakers is, of course, getting the lowest octave and a half in your price range. It might not be possible without spending more or adding a subwoofer (or speakers with built-in powered subs).