Weather systems seem to move acroos at 6-7 day intervals. While the paths seem generally to the NE sometimes they are from the NW. In rough terms one might estimate the W-E component at say 8 knots phr. To that add the boat speed for that type of boat to get a relative speed of 12 knots/hr. That gives a system change of four to five days. Since the trip EW would take 12-15 days that gives three systems at least. Probably a low in the middle and the first part of one at the end. Coming the other way one might stay in the system for 12 or more days staying in one high.
I doubt that one would get 9 days in a high going EW. Of course some are slow moving but I wouldn't expect one in Sept. One might do better going somewhat north. There are monthly charts
of the prevailing winds that should be referred to in planning. I am not going into that detail.
I just suggest EW is harder and while you are unlikely to get a cyclone, you are likely to get a rough patch with a long fetch so big waves. You may also have a bit of a wait for a better weather window. Hence the quite strict cat one regulations
and the need for experienced crew.