I'm hardly a road warrior, but I do own an Interblock 45. I think that it sounds very good. I generally play clean, and I like the sound of tubes. I like a tweed tone a bit more than a blackface tone. In other words, I like more mids with a slight raspiness to them than pure clean. The Quilter itself isn't quite that. To my ear, at home with no backing music or other instruments, it has a bit more presence than a tube amp. I haven't been able to dial that out. If you play with more dirt or, as you said, at practice or a gig, I do not know if that presence would be noticeable. I used to have a functioning Microblock 45 that a buddy and I used for the power preceded by a Joyo American Sound into a Tech21 ParaDriver. There was a lot of other sound in the room as we played through it and I did not hear the extra presence. I thought that set up was easily capable of substituting for a tube amp. I think that the I45 itself might work for your intended applications.
A cautionary tale, the reason I say that I used to have a functioning Microblock 45 is because I accidentally fried it about a week later at home. I was switching the speaker I was using while the M45 was still powered. I dropped the speaker cable and the tip and sleeve touched the metal leg of an amp stand. Apparently, Class D amps do not tolerate a zero ohm load, even for a second. It was a tough way to learn that lesson. Always keep the power to the Quilter off until you have a speaker plugged in using a reliable speaker cable. At most, unplug from the Quilter first rather than from the speaker cabinet or your combo amp's speaker.
Just the other day, I experimented with the I45 and my Supro Blues King 8. The ParaDriver into just the I45 did not have the magic of the Joyo and M45 that I had heard at my buddy's house. The Supro has a line out after the 12AX7 preamp, before the 12AU7 power amp. I wanted to see if I could get the tube characteristic second and third harmonic from the Supro's 12AX7 through the I45 minus the extra presence of the I45 alone. So I tried. It sounds really great. Very, very close to the sound of my Tungsten Crema Wheat (tweed Deluxe inspired, fantastic amp). Truthfully, I think that they could be dialed in to sound so similar that I would be hard pressed to pick which is which in a blind test. I'm using the CW's Eminence Li'l Texas for the Supro-I45 experiment, so neither the speaker nor the cabinet is affecting the results. On the I45, I plug into the Input, use the Vintage EQ Voice and select the Cab option at the speaker output. I tried plugging the Supro into the I45's FX loop return to use only the power section, but I like using the I45's preamp to get a bit more tone shaping than the Supro's single tone knob. This has gotten me curious about how a good, high voltage tube pedal-style preamp going into the I45 would sound. In particular, I'm intrigued by the Surprise Sound Labs Rock Block and several of the Kingsley offerings, particularly the Squire and the Maiden. But I'm not trying to hijack this thread.
Anyway, I hope that you find some of the above useful and sorry if I overshared.