Can you describe, many people can't, what you feel the Clio is lacking to make it a more interesting/ exciting car to you?
I remember the first one that I had. I was absolutely sick to death of driving it. Revving the engine hard, Honda-esque, was never something I was particularly attracted to. I used also use the car for two 170mile drives each week, and little else.
When I got the car onto some twisties, I was so frustrated by traffic that I tended to drive it as hard as I possibly could on the twisties. Less than inspiring. I consciously changed the way I was driving the car. Instead of driving it hard, I tried to maintain progress at 60mph regardless of what the road threw at me (obviously within reason). As opposed to driving the car quickly I began to exploit the chassis and see what it could do. Gained a whole new love for the car.
That and I got out on track!
The one thing in relation to taking a Glanza for a test drive, they feel quick, they feel a lot quicker than they actually are (as is the case with 90% of turbo cars). Turbo spool vs n/a acceleration. You're also unlikely to really try the Glanza in the corners, who wants to crash a car they're only testing.
Ultimately, it's you're choice I suppose. I personally wouldn't even give a Glanza the time of day. They really are THAT bad. Fantastic for traffic light drag races, not great at much else.
Have you looked at Ibiza Cupras? Probably slightly slower than the Clio overall, but with the 20vt engine, should the need to modify and up the power come later down the line, you already have a fantastic base and a turbo developed engine ready to rock.