It is incredible that people still promote these myths.
Both versions of FF&S are comprehensive and very usable, once you get past the typesetting error in T4 FF&S, and there is a lot of very useful stuff to be found in T4 books.
If the maths is too difficult someone will be along with a spreadsheet version for you in time...
(Mongoose you own them - update and adapt Pocket Empires and Imperial Squadrons please)
The proposal I made is for a technical construction manual for Mongoose to be constructed using FF&S, and any other design sequence that can be adapted.
Real world units for energy, mass, volume, surface area
This underpins every design sequence. Simplified version can be produced that abstract things like displacement tons or pods or whatever,