Taig CNC Mill vs.Homebuilt Machine

I have read with great interest many archived and all current
postings since joining this Group. I am encouraged enough to move
from the periphery and into the fray and would like to know whether
there is a compelling reason to buy a mill and modify it for CAD/CAM
use rather than assemble one from discrete components attached to a
welded frame, whether in traditional mill form or gantry.
I have been leaning towards building as it seems to promise larger
than "benchtop mill" size and I have several ball screws, linear
bearings, motors and drivers. I have believed that the use of these
components is inherently better than leadscrew and dovetail ways in
obtaining a tighter tolerance and longer life. My specific concern,
however, is the linear bearing's ability to withstand repeated stress
and my ability to construct a frame to proper tolerance.
On the other hand, the temptation to purchase a CNC ready Taig is
justified in my research having yet to read a single complaint or
regret. I could even us it to build a gantry mill as my second
machine.
I appreciate this group and have been impressed by its contributors
namely Les, Tim, Wes and Jan to name a few.
Sorry Bill, is that flaming?

Thanks for the consideration,
Bob O'Neal