I wouldn't worry so much about the parts as the sound. My Jadis preamps had parts in them that may not have been the most expensive, but the end result was stunning.
If your dealer has both brands, can't you listen to them there and compare? Or better yet, borrow them to try at home in your system? That way you'll know if it sounds better to the only ears that matter, yours. Look at the above posts--there are two people who have differing opinions of the Prima Luna vs. McIntosh. I would say they are both correct, as far as their own hearing and personal preferences in what they want out of their audio systems go. You need to make your decision based on what you hear, not what someone else says.
If your dealer has both brands, can't you listen to them there and compare? Or better yet, borrow them to try at home in your system? That way you'll know if it sounds better to the only ears that matter, yours. Look at the above posts--there are two people who have differing opinions of the Prima Luna vs. McIntosh. I would say they are both correct, as far as their own hearing and personal preferences in what they want out of their audio systems go. You need to make your decision based on what you hear, not what someone else says.