I've been lucky enough to try the GS-Mini Mahogany, GS-Mini-e Spruce and a few of the Taylor GS range (Koa and Rosewood).
I ended up keeping the GS-Mini Spruce - it has a lovely clarity and brightness without losing anything in the bass. The Mahogany version felt a bit warmer and muted. My partner didn't like the sound of the mahogany version at all. Her first reaction was "that doesn't sound like a nice guitar to me" which was enough to put me off. The GS-Mini-e spruce has a mahogany body too but that spruce top makes a huge difference.
I played the Taylors last and found that while they are finished to a very high degree, they suffer similar problems to the HB guitars - once you get to the upper registers on the fret board, a boxiness creeps into the sound, especially on the wound strings. That's the tradeoff for these smaller guitars. The Taylors have better components all around, nicer neck (I really don't understand why HB went with a soft V for their GS-Minis and it feels quirky even now) and better fretwork.
The other important point here is that the HB GS-Minis need a bit of work in the beginning, particularly frets and fretboard.
1. I took the saddle out and removed the scrap plastic they dropped under there. If you have the e-Version, the scrap is actually under the pickup. Also, check the saddle slot is clean and smooth - mine had routing errors leaving steps in the walls of the slot that needed to be smoothened out. And look for woodchips at the bottom and clean the drill holes. An easy fix. I then bought Graphtec's "Supercharger Kit" to replace saddle and pins with tusq quality components. Wow - big difference! It's a shame Thomann doesn't sell these kits but they are not hard to find, amazing value and definitely worth the investment. The one you need to get is "Graph Tech Supercharger Acoustic Kit B (9280-10)" which comes with slightly thinner bridge pins. I still had to file out the groove in the pin for the low E string as it wouldn't fit. Just mark it with a sharpie so you remember which one you filed. The other pins fit without modification and the saddle only needs slight sanding for your preferred saddle height.
2. Frets - I gave mine a full fret level, crown and polish. The GS-Minis have pretty horrible frets - both of mine were dirty/rusty and all over the place from a levelling standpoint. The levelling beam sorted that out and crowning file and sandpaper cleaned it up. This step makes a huge difference to playability.
3. Nut - the nuts on the GS-Minis weren't too bad but getting them to the right level after fret levelling is worthwhile. I used proper nut files to take out a bit of material. Only a couple of passes are required because the nut is plastic so be careful. I will probably replace this with Tusq nut soon as well.
4. Action - I thank the guitar gods that HB put truss rods in these guitars. It allows easy adjustment of the action. I also took about 2/64" off the bottom of the saddle. Both of these helped getting the action SUPER low: I've got 3/64" on bass strings and a smidge over 2/64" on high E. Only a little bit of fret sizzle but that adds flavour to these acoustics as they can be a bit sterile given their size.
5. Fretboard and bridge - dry as hell. Put some lemon oil or Ballistol on those and bring them back to life!
For those wondering about the pickups - I was genuinely surprised. They aren't as bad as you would think for an under-saddle pickup. In fact, you would struggle to hear much difference with higher-end guitars because the pickup system is the limiting factor here. My only gripe is that the pickups are active - I'm going to install passive pickups next.
The guitar bag - wow! Really solid quality soft-case guitar backpack. Decent padding and design. Probably used the same factory as Taylor's GS bags ;)
After a few hours work, the HB GS-Mini-e sounds and plays fantastically well. I currently have Ernie Ball strings on it and they are a match made in heaven. They just sound gorgeous and sweet. The Martin strings I had on a few weeks ago were amazing as well. The Fender strings I tried sounded flat so best to stick to Martins or EBs.
I probably added a few hundred dollars of value into this guitar taking into account the effort and replacement parts and other than the weird V-neck (which even Thomann's own video reviewer was struggling to comprehend), I couldn't see much difference with the higher priced Taylors.
Of course, once you get to Taylor's Koa mini, you start to see a big difference and it really stands out - the sound is very special but the cost of that guitar is hard to justify for a throwabout or couch guitar. I should add that Taylor's entry level GS series guitars do not use one-piece spruce tops - they are bookended 2 piece which some say can affect sound. The HB appears to use a solid one-piece spruce top. The bodies on both guitars are laminates of some sort.
I should add that the HB guitar doesn't look like it will last forever - the fretwire is pretty soft and discolours quickly so once you wear those down, you're going to have to get a new guitar. I can't imagine the fretboard will survive a re-fret but I would love Thomann to confirm otherwise as I would love to be able to do that on this guitar - it really ticks a ton of boxes for musicality and playability.
The only major downside I've discovered after a few weeks use are the tuners - mine wouldn't hold tune very well and had plenty of backlash and some dead spots where turning did nothing. They would be easy to upgrade and replace - most Gotoh tuners should work as they use 10mm bores.
Oh, and definitely go for the spruce top - it sounds "more like a guitar" according to "she who must be obeyed".
Blimey, this thing really rings!