Ok, my experience with this tactic...
... was very positive.
In my save I manage HSV, and played the first 6 seasons with Koflok's Goals Galore. Won the league twice, the cup twice, the Europa Cup once and the CL 3 times. I liked the tactic because it's elegant, sound and relatively close to the system HSV plays in reality.
But I got bored and wanted a tactic that scores more goals, so I decided to make a change and try something more adventurous.
So, I tried Casey's and just finished the first full season - winning everything apart from the German Cup, and I got some amazing results on the way:
7-1 vs ManU in the CL k.o. phase,
8-1 vs Bayer just hours after HSV won the league (it was a Saturday evening game). There were more great results - 4-1 vs Bayern, 6-0 vs Porto, 7-0 vs Hoppenheim, etc. Of course there were also a few other games where HSV created chance after chance but failed to convert and dropped points, but those were few and far in between.
Note that Casey's didn't improve the points total (which would be almost impossible to do), but scored about 50% more goals and had far more exciting games.
I attached the respective screenshots:
1) HSV's performance in the league over the years: around 80 points since the team had been built up, averaging 80-20 goals. Then Casey's season: 123-35 goals. One hundred and twenty three.
ONE HUNDRED AND TWENTY THREE. The record in reality is 101 by Bayern when I was a baby in 71/72.
2) The stats vs ManU and Bayer, total domination and an abundance of CCCs.
3) Overall, Home and Away Bundesliga table. Casey's scored more goals at home than Koflok's in total, and all games were won.
4) The player ratings of the Bundesliga - HSV had 11 in the top 15. That's partly a result of the tactic as goals improve ratings, but it is also something to bear in mind - this is a team that has been built over the years and is far and away the best in its league.
Overall I am very happy with this tactic, I like how it creates chances and how devastating it is on the break - I guess about a 3rd of the goals came in the last 20 minutes.
Not sure if I would start a game with it, though - it seems quite risky.. But maybe I'll try it from the start in a new save.
Btw: I made no changes to the tactic apart from different set piece routines - 26 goals were scored from corners, about 10 more than before, I'd say as a result of getting more corners due to a more offensive tactic.