In reply to Removed UserBlaseSlayer:
The difference is the groupset (shifters, drivetrain, brakes). The 100 has the entry level Shimano Claris groupset, while the 400 has Shimano 105. 105 gives you lower weight and is 11-speed, while Claris is only 8-speed.
As for Merida, they're well made bikes at a reasonable price with the Scultura classed as the lightweight/climbing model.
Personally, I'd hunt about on the used market for a good quality rim brake 105 bike. Bikes are a lot like cars - they depreciate massively in the first year, despite the fact there's nothing wrong with them! Plus as the industry is pushing discs, used rim brake bike prices have plummeted in the past year. You can pick up a two year old carbon frame rim brake Giant TCR, Trek Emonda, Scott Addict etc for under £1,000 and use the savings to buy a decent headunit and a quality pair of bib shorts.