I've only heard the latest bookshelf Missions, and they were fantastic for the price. And I do own a pair of 600i from the mid-90s, which have always sounded well for their size and price.
If you are thinking of the MX3i, the model that Richer Sounds are selling for £169, I think I'd choose instead the award winning Tannoy Eclipse Three, reduced from £299 to £199.
I'm sure with a bit of warning a RS store could demo all three from which to decide.