Nice comments on other Gulfstars but the Sailcruiser 54 is a bit different from most Gulfstars. I believe this boat is a true motor
sailor. Twin diesels and a 55' mast
on a 54' boat. I have a somewhat short rig on my Pearson
42 and it's almost 52' for a boat that's 12' shorter than the Gulfstar.
I have not sailed the Sailcruiser but I would think the performance under sail similar to the Sailmaster which is not a fast boat. Typical of big boats with small rigs for their size and displacement
the light air performance will be limited, but can be helped a lot with large, light weight sails
. Pointing also not the best. However, the boat will sail and with a bit of wind will give you reasonable speed, especially off the wind. If the motor
dies you will not be stuck looking for a tow.
If you are comparing them to a motor sailor type where the sail is just big enough for steadying then the Sailcruiser will blow them away. But compared to a "normal" sailboat you will be much slower.
Here's a link to a review of the Sailcruiser if you have not yet seen this.