I'm using the Line6 HX Stomp to 1) drive my speakers, 2) as an effects unit in the effects loop of my amp, and 3) as a silent practicing tool with my computer. All of this at the same time, which is incredible.
The unit itself is fantastic. The amp models are amazing, cabinets are great, ability to upload impulses is also spectacular. Sounds great!
Three areas where I would still be careful. First, practicing with headphones is SUPER dependent on the headphones. It sounded terrible until I got a pair of Sennheiser 650s, thanks to the open back and high quality speakers. If you want to use it for that, calculate extra costs for good headphones.
Second, my unit has frozen once or twice, forcing me to factory reset. I'm pretty sure this is due to a driver conflict with the computer, but still something to keep in mind. It is a super complex piece of kit, so you CAN run into issues with your other hardware.
Third, this thing can do so many things that the learning curve is very steep. It took me a few weeks before I found sounds that worked for me.