Do those 703s have the infamous yellow Kevlar mid-range driver? At that price, they probably do. If so, my short answer is don't buy them.
In the long run you will not like them, and put them up for sale. Their bass is far from tight sounding, but that can easily depend on the room they're in, where they're located within the room, and where you are located too. Their upper and mid range sound will be too bright sounding. It may seem tolerable at low to moderate volume, but at higher volume they will sound harsh, ear-fatigue-inducing harsh.
While it is true that used B&W speakers do sell for decent prices, it is also true that many B&W owners become disappointed with their speakers. The used speaker market is full of them. The main reason is those yellow Kevlar mid-range drivers. They should never be crossed over to the tweeter at such a high frequency of 4,000 Hz. They make harsh noise at that frequency. B&W has tried a variety of ways to suppress that noise. Most of those efforts don't work well, except in the much more expensive 800 series speakers.
Here is a visual comparison two mid-range drivers producing a 3,500 Hz signal. On the left is an unnamed (B&W?) yellow Kevlar 6.5" mid driver, and on the right is a similarly sized driver made by Revel. The cone of the left is clearly in what is called 'break-up mode'. I'm rather certain people would not like its sound.
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