I've had 3 shaves with mine before I started playing around a little.
Stock, I found that the threads on the handle and top cap aren't the best of matches, they could be smoother. Oddly enough, the handle is very smooth with just about any other top cap and the Meta-4 top cap is very smooth with pretty much any other handle.
Positives so far:
- smooooth (but see negatives),
- decent efficiency, just a hair below GameChanges 0.84 SB, but smoother,
- stock handle is reasonably grippy (but not above average),
- blade tabs covered,
- top cap (in fact, the whole head) is really thin,
- I like the matte finish on the top cap,
- fun can be had with the top cap.
Negatives so far:
- the top cap and the base plate meet primarily clamped at the edges. This means I needed to pay extra care to tighten the handle well enough, otherwise the shave is rather rough.
- The head is about 1mm wider than it needs to be to cover the blade tabs. This means that shaving right under the nose horizontally can be challenging even with the nose nudged to the side. However, because the top cap is so thing, shaving downwards and upwards is actually very easy, so it rather makes up for that.
Notes:
Top cap fits the Colibri base plates I have (1.3 OC and 1.5 SB). Only one shave in so far and I suspect the blade had been on its way out, so I need to give it another go. Preliminary observation - actually lot smoother than with the stock top cap. Need to re-test with a fresh blade and compare again, though.