I've been alternating Merkur Platinum and Derby Extras for the past few weeks to see which I prefer.
It's kind of a mixed verdict:
The Derby provides a good close shave, but seems to start off almost too sharp and then dull very quickly. Usually my first shave with the Derby leaves me a little raw feeling, especially on the neck... but by the third shave it is noticeably less sharp and almost dull by Friday (it's not really dull, but markedly less sharp than day 1).
The Merkur doesn't seem as sharp but I can easily get good consistent shaves all week... typically when I change the Merkur it is only because it is Sunday and that's the day I change the blade.
It's kind of a mixed verdict:
The Derby provides a good close shave, but seems to start off almost too sharp and then dull very quickly. Usually my first shave with the Derby leaves me a little raw feeling, especially on the neck... but by the third shave it is noticeably less sharp and almost dull by Friday (it's not really dull, but markedly less sharp than day 1).
The Merkur doesn't seem as sharp but I can easily get good consistent shaves all week... typically when I change the Merkur it is only because it is Sunday and that's the day I change the blade.