Which Harbeths?

OP: I agree with akg_ca’s assessment of the 30.2’s. Treble and midrange are wonderful. Vocals sound lifelike to me. I did not intend to suggest that these speakers are in any way less engaging than the C7ES3’s, only that the latter are musical as well. In my estimation, the C7ES3’s are a better value than the 30.2’s and offer enough more bass for that to be noticeable. They are, after all, larger. If your finances allow the extra expense of the 30.2’s, I don’t believe that you will be disappointed at all. My suggestion is to keep an eye out on the sites where used, demo, and open box models are sold, and look for a good deal to appear. I owned the C7ES3’s (demos) for about five years and sold them on for about 75% of what I paid. You would likely lose relatively little if you decided to flip them in favor of something more costly. My 30.2 XD’s are also demos and were discounted about one third off list price. 

My experience is exactly the same as conlad. I don't believe you'll be disappointed with either speaker.

Having heard harbeth 30.2 40th anniversary and Graham Audio ls 5/9 side by side for a few months, I can say that I love the BBC sound and I really love the Graham Audio execution better. If you like the treble of the 30.2, you don't know what your missing with the similar grahams. Way more open up top but not harsh, even better balanced. Beware, to get the most of these speakers bass wise, a powerful amp is required. 

I owned Harbeth P3ESR about a year ago, and currently own 30.1 (home office) and SHL5+ (media room). I auditioned C7ES3 last year, and 30.2 a few weeks ago. Based on my preferences (and mine only) ...

SHL5+ > 30.2 > 30.1 > P3ESR > C7ES3

If you are comparing 30.2 with C7ES3, I can tell you that they are very different from each other. Both have their fans and detractors. I know you don’t want to hear this, but there’s no way to know which one you’d like without auditioning. But if you have to roll the dice, I would say 30.2 is a safer bet ... it is more balanced and refined, but at the cost of deeper bass, and is not as romantic and lush sounding as the C7s.

For a small’ish room, say around 10x12 or smaller, very few speakers can beat the beautiful sound of P3esr’s. IMO, when it comes to vocals, P3esr’s are still the king of the hill in the Harbeth lineup.

Just my 2 cents.

In as much as I haven't noticed or perhaps overlooked any  comments pertaining to my question, - - - - are you planning on buying one or the other HARBETH speakers without an audition? If you have, or plan to set up an audition, then without question, the final judge are "your ears". You certainly shouldn't be buying speakers based on specs or reports or recommendations. There are so many variables associated in choosing the right speaker that fits your system, room acoustics; - -  well, you get the idea. But most of all your specific taste in music, has to play a very important role. 
HARBETH is one of my top two speaker designs. However the different models can sound quite different, when you take into consideration the factors I mentioned. Unfortunately many people think a person can buy speakers based upon specs, reviews, or recommendations. It seems to me that what your trying to accomplish, falls into this category. Room size (a very important part of the acoustic equation) is especially important. Realistically speaking, you may find yourself needing additional support in the lower octave frequency range, with either speaker mentioned. Again, depending upon taste and the type of music you enjoy, and let's not forget the decibel level that you are accustomed to play the system at; - - -  all these are important considerations in your decision making. Naturally, budget is obviously a consideration as well
Both speakers you mention have received glowing reviews by virtually every audio periodical in the world. Actually, that doesn't help.
If cost was no object, I would actually recommend  the "world class" 
40.2. Truly a loudspeaker that can handle any room size while retaining  all of the nuance and audible characteristics of the rest of the wonderful HARBETH line. And I would go further to add that the 40.2 is at home with virtually and genre of reproduced music. 
GOOD LUCK.