Which speakers do I pick and are they close in quality

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?

Its your money you pick.

With all due respect to akg_ca, I’ve had a pair of Totem Forests for over 10 years. The metal dome tweeter CAN be hot and harsh, especially with poorly recorded music. It took quite a bit of experimentation to figure out how to tame it. That won’t be acceptable to everyone. With the right amplification, cabling, tubes and room treatment, the treble can be nicely managed without compromising the excellent imaging these speakers are capable of. Using the Forests for 3 hour + listening sessions with no fatigue is not uncommon for me. Re-reading your post, I see you already have the Forests, so I’m "preaching to the choir" (maybe).

As far as being power hungry, I used to believe this too. See BlindJim’s thread, something along the lines of "Which Watts Are The Right Watts?". Recently, I was very surprised how good the Forests sounded driven by a First Watt F7 amp (20 wpc). Georgehifi weighed in with some commentary relative to the Forests begin an easy-to-drive-speaker.

I’m certainly NOT trying to tell you to keep the Forests and forego the Harbeths. Simply providing my experience with the Forests. I think you should get the Harbeths - at least for an in-home audition. If you find they are only a different flavor and just a lateral move, consider keeping both sets if you have the $ and room. Always nice to have alternatives for a change of pace.

For about the same money as the M30.2 anniversary edition you could get the ordinary Harbeth Super HL5+. In a largish room such as yours, it would probably be a better buy.

I doubt that you will go wrong with the Harbeth. I own the smaller P3ESR and it blows away any other small monitor that I have owned. Here is a review of the M30.1. It is basically the same speaker as the M30.2!
http://www.theabsolutesound.com/articles/harbeth-monitor-301-loudspeaker/
And another!
http://www.6moons.com/audioreviews/harbeth5/1.html