Harbeth 30.1 upgrade from C7ES-3 Question

I bought one of the last sets of Foundation Stands for the 30.1 in anticipation of one day upgrading my C7s but I haven’t been able to pull the trigger yet. I’m interested in general whether this is a slam dunk upgrade, but specifically if I may not get the bump because I listen in the near field. In other words, does my listening position decrease the impact of the benefits of the 30.1? Or maybe it the other way around and it’s an even better upgrade for nearfield listening? Buying used so a demo is not an option unfortunately.

I've enjoyed the C7s for three years now. I listen to all kinds of music except not much rock and classical. Jazz, blues, gothy folk electronica in heavy rotation these days. Thanks in advance...
You might notice a  difference. I moved from he C7ES-3 to the SHL5 Plus. I’ve heard the 30.1 on a few occasions and I really liked it a lot but not enough to pull the trigger but i also don’t listen near field like you do. If you didn’t listen near field I’d say don’t bother but in your situation it might be a worthy upgrade. For me, the SHL5 Plus with the additional tweeter opens up the sound stage and lends itself to my larger room. I also added stands from Resonant Woods that have open bottoms and that made a noticeable difference (my dealer leant me closed bottom stands like Skylan until my stands were delivered). What stands are you using with your C7’s? The stands make a huge difference. I don’t care what Alan Shaw says about the speakers sounding good on a chair or a stack of books. I say "NO" to that. When I had my C7’s on Skylan stands, I ordered these things called Q Bricks from Skylan and it made my speakers sound like I covered them with a heavy wool blanket. My wife and I were shocked at how it sounded and I immediately removed them.
I'm using Foundation stands and I already have 30.1 Foundation stands that I got from a friend when he upgraded to 40s. It's a tricky loft kind of room, actually large but then split by a room divider. Speakers sit in the middle, clear of any walls. I think it would be a perfect setup for the SHL5+ but they take up to much space. 
I'm on same boat as you ,and pull the trigger and got the M30.1.
my room as start is small 9x10 both with C7 and M30 ,me listen at moderate level but not too loud.
the C7 give me the bass I want in smaller room ,
but the midrange on M30 is what I love ,is so natural ,I lost some bass but found lively sound .
that is what I sacrifice for ,also most I listen is vocal Jazz ,female singer is unbelievable on M30.1 .
now my listening room little bigger is 10x12,you can check my system here.
PS: If money not problem go for it !

It’s more like a slam dunk difference rather than upgrade to me. Best if you can listen to the M30.1 before taking the plunge as it sounds quite different from the C7ES3. Although the M30.1 is technically a superior speaker, I prefer the presentation of the C7ES3. With vocals and small ensembles the 30.1 may have the edge though, sounding richer and more lifelike than the C7ES3.

Donjr - similarly I find speaker stands to make a difference on Harbeth speakers. I have tried heavy 4-pillars with top and bottom plates (24" and 16") and lightweight open-frame stands(17"). The SHL5 Plus sounds different when placed on all these stands. Intrigued by your remark on the Q Bricks, I went over to the Skylan site to check these things out. I would have to say, the description of the Q Bricks is rather rhetoric, "vibrations are completely annihilated". Who would have expected the Q Bricks to make the speakers sound like someone covered them with a blanket when they are supposed to open up a new soundscape.

Skylan stands with SHL5+ and love the sound. I lived and loved Harbeth LS3/5A's for 15 years then a few years of the lovely KEF LS50, now the SHL5+. I suggest you go with the 5's.

I now have both the C7s and the M30.1s in house. Don't know that I'm hearing a $1200 difference. Giving up bass for a degree of purity of midrange is a tricky trade.
I echo what some of the others have said. I am not sure it is a worthy upgrade if it is in fact is an "upgrade". You will lose the bass to gain mid-range which may or may not be something you want to do. I owned the C7's for a month before returning them for 30.1's. My musical tastes are soft jazz and female vocals so 30.1's work well enough for me. For more dynamic rock music, these speakers are so lacking in bass that I am thinking of supplementing them with a subwoofer. If I wanted to upgrade from the C7's I would jump another level to the SHL5's or the pluses. 
After further listening, I'm thinking it is an upgrade. I feel like the purity of voice and instrument has grown on me and swapping back the C7s is a bit unsatisfying. Definitely hear more of an edge to the vocals and in general everything is a bit looser. I don't listen to rock at all and that's where the C7s are as good or better. For my electronic, jazz, blues, folk habits, I think the 30.1s are a nice upgrade since I have the $1200 to spend. If I didn't, I probably wouldn't go into debt to get the 30s and based on everything I've read about the SHL5s, they don't fit my needs. I'm set for now.... until we move and I have room for Quad ESL57s again.
Additionally I must add that low level listening is way way better with the M30.1s. I still have the C7s and side by side it’s an obvious advantage.

Just trying to help others who are considering this upgrade.