Somebody is sure to take issue with  my following comments.    Whatever..
 I make them based on the experience of my friends and neighbours, rather than personal  experience..  

So  FWIW...

if you have real rock, you probably wont like the  Bourgalt Hoe drill.  
But if you have had a Conserva pak  for 7 years, then I can surmise you dont have much real rock.   

"Here"  a Conserva -Pak  or whatever Deere now calls them, will be pretty much destroyed in one season.  I have friends  who  managed to do that.  They have since gone to a K Hart disc seeder,  and have spent the last 2 or 3 seasons  working through the many issues with that, but report to me they  think they are on top of it now., and had good rersults generally last seeding.

The Bourgalt probably wouldnt  be destroyed in one season, but  you would spend a lot of time replacing parts during the season.  The obvious question is "what parts??"  and since this is not my experience I cant say, but my next door neighbour had a new  one  last season (dont know the  Bourgalt model hoe seeder), and had  immense  problems with breakage and bending problems, to the point that he has replaced  it for this coming season. I have no idea what he  thinks of the Bourgalt aircart, but his thinking is likely coloured some by his sad experience with the seeder part.           His previous Flexicoil hoe seeder and 3450 aircart he had for something like 8-10 seasons I think.

I think it is generally acknowledged that we have "difficult" soil  conditions.