No way around it - changing substrate is a big and messy job. But can easily be done in 1/2 a weekend day, or a long evening. One thing to guard against is after you get the old clown puke out and the new stuff in, you have to replant everything. You want to make sure you aren't too tired or rushed at that point to do a good job trimming and separating your plants and placing them optimally. You could easily just float your plants for a day or 2 and do it in 2 stages.
I find your current scape pretty pleasing. Doesn't knock my socks off, but surely not offensive. Mice selection of pretty bullet-proof plants.
A couple of thoughts - I don't see any significant hardscape - rocks or wood. Hardscape establishes focal points and provides interest in many scapes.
Also, I would bring something up closer to the front glass. Either one of your existing plants, or a shoter foreground plant. The strip of substrate across the front is uninteresting, and emphasizes the consistent height in the rear.
If you posted your params - light, ferts, CO2 - it might affect our recommendations.