I've had this unit for about three years now.
It sounds amazing through headphones/speakers. I haven't used it with a tube amp, so I can't give my opinion on that.
I used it mainly for experimentation and figuring out what kind of effects I would actually use and for playing around with tones, and it's very useful for that.
Nothing I've tried comes close to it in terms of usability. Don't get me wrong, you still have so many options that you might end up having a hard time knowing which to choose, but the user interface is second to none. That was the main attraction for me, no need to dive into a million menus: just choose an effect/amp, tweak it with the encoders and that's it.
Quality wise, I have only one complaint: the expression pedal gave out rather quickly on my unit. I didn't break, but it just stopped registering movement(maybe the optical sensor got covered with too much dust).
However, Line6 replaced the unit on the spot when I told them about the issue, so kudos to them. Best customer service ever. I think they issued a lifetime warranty for Helix LT expression pedals.
HXEdit, the editing software works great and is really useful if you keep your unit on the floor.
The looper could use some extra time on the loops, but it's serviceable.
All in all, I don't think you can beat it. It has more effects and amps than one person can realistically use, but that means that everyone can find anything that they need inside. It's very intuitive and doesn't get in the way of playing as much as other menu heavy units. Snapshots and presets give you a ton of flexibility. If you do need to tweak things, it's the best user interface I've ever seen on a processor.
The price is amazing for what you get(trust me, I'm looking at building an analog pedalboard with the features that I used on the Helix and the bill is stacking up quickly). The HX Stomp does almost everything that the LT does, but I have a feeling you lose some of the ease of use and a significant part of the processing power with that product.
Oh, and for a home guitarist, an aux input is invaluable. It doesn't have one, but you can use a split stereo cable and the effects returns(there are two of them), if you aren't using the for external pedals.
