I should also re-iterate, I don't feel any certainty about whether or not the fatboy is fine right now, I just think a lot more experience is needed with this mobile factory change.
For example, while taking those screenshots, above, and testing a tiny bit, I noted how much turning the fatboy's rear to the enemy just before a parashield pops out can help.
Fatboy's can be driven backwards - this will also probably help a TON when building parashields, and it's something I haven't tried! Hell, building t3 combat units would probably make a massive difference there, too!
Until players have a 'feel' for what kind of resistance merits going in 'ass-first' with the fatboy, and similar understandings of the changes, I feel it's hard to know how good the current unit is.
The only thing I will say with confidence is that the mobile factory functionality was a significant buff to the unit.