Harbeth 30.1 upgrade from C7ES-3 Question

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 !