I have used my Z-Force 48 for one full season. I purchased it with a bagging unit (the cheap one without a blower on it) and a mulching kit.
The mower works very well, and in mowing my 2 acres with many obstacles (trees etc.) has made a huge difference in how long it takes. Driving it took some getting used to, particularly to not spin the wheels when turning a square corner and so tearing at the lawn.
The bagger works okay as long as the grass isn't too long, but if it plugs the tube up, then that's a major chore to unplug.
The mulching kit works very well - I didn't use it until autumn leaf time, but it can mulch several inches of leaves away to almost nothing visible in one pass.
The build quality is good, but there's room for improvement - for example there's no provision to adjust the tapered roller bearings in the blade spindles and I noticed at the end of the season that all 3 are loose - there is end play in all 3 spindles, which apparently can't be adjusted, or can only be adjusted by shortening the spacer between the 2 inner races.
The time limited warranty isn't great - I consider with a bit over 2 acres I'm probably below average user, yet have done 105 of the warrantied 180 hours in my first season - so warranty will expire before my second year is up - let alone the 3rd year the warranty is supposedly good for.