Two completley different sounds.
The Monitor 30 isn’t bass heavy but has a beautiful midrange and balanced sound. The Forests are pretty "energetic" sounding and do a fine job filling a room for their size. If you primarily listened to Pop or Electronica I’d recommend the Forests. IMO Harbeth speakers pair nicely with McIntosh gear and you would end up with smooth engaging sound. They may better suit your listening tastes. Only you can decide if it’s worth the price difference. Is an in home audition possible?
The Monitor 30 isn’t bass heavy but has a beautiful midrange and balanced sound. The Forests are pretty "energetic" sounding and do a fine job filling a room for their size. If you primarily listened to Pop or Electronica I’d recommend the Forests. IMO Harbeth speakers pair nicely with McIntosh gear and you would end up with smooth engaging sound. They may better suit your listening tastes. Only you can decide if it’s worth the price difference. Is an in home audition possible?