I haven't  scrutinized landoll vs.  sunflower...  it  seems like they are  very very similar when comparing them-- generation to generation.  
why the blue one's   more popular..   
Landoll  does offer adjustable gang  angle,  and  slightly narrower  blade spacing for more of a  'high speed'  if you want to  'tune' it  in that regard. 
---can't argue the  shiney blue looks nice----

I run a  1434-36 I bought used  10 yrs. ago.   It's been a heck of  good disk. 
18,200#'s total--- about  505 lbs per foot. 
 I'm not looking forward to re-blading it this winter,  but other than the  blades,  there's no reason for me to  not keep it.
 
Mine  doesn't  have the optional power leveling..  not sure it's really worth the extra $$$'s.  

 don't forget to grease the  walking tandems!!