Sorry - I meant that the Vox amp becomes dirty very gradually, while the amp with negative feedback will tend to have a narrower threshold between clean and dirty. It's just a different style of amp. I know some guys like to have the ability to control clean or dirty according to pick attack and some want an amp that will give a consistent sound however hard they attack the strings, with just an increase in volume.
I did experiment with -ve feedback in a small single ended amp I built a while back. TBH it wasn't impressive, although it did tame output quite a lot until I reduced the feedback a lot over the suggested value for that circuit. It might be interesting to build the feedback loop with a pot & baseline resistor, although it might just be a waste since I'd probably just find a favourite level and leave it there. It did try that with preamp valve bias in the first amp I built, but ended up with a 'best tone' setting and eventually replacing that with a fixed resistor at that value.
The Spider is at the food grade end of Line 6 stuff, but TBH all the older stuff incuding the Vetters and Flextones suffer the same basic fault - too much high frequency hash and not enough punch in the mids, though the more expensive amps are less intolerable.
I owned and used a Laney Protube 30 for a while. It was supposed to be Laney's answer to a Boogey, but TBH it was tonally compromised outside the high gain overdrive settings (and wasn't great with those). I did speaker and valve swaps, made up open backs for the cab all to no avail, which was a shame because it sounded like a great rock amp in my livingroom. The one good thing is that I bought it for £50 and sold it for about £90. Wish I'd kept it and built something else with that iron and chassis, because the transformers were HUGE and the chassis vast.
With a small amp like that the speaker (and especially efficiency) makes a HUGE difference. I used to use a little single ended amp that I ran with a 6550 for about 20 watts. Volume was never an issue with various 10" celestions until I popped a Jensen P10R in there. Efficiency was around 93dB/watt, and although it sounded interesting, it really couldn't cut it, even with just 40 or 50 people singing. Conversely I used another home grown 5W SE amp (1 X EL84) that was fine for volume with a G12H (100dB/watt) in a largish semi-sealed enclosure.
The one thing the small amps really lack is bass, mostly because of the small output transformers. It all depends on the sound you want, but if it needs a bit of a kick in the bass then a much bigger than typical OT is called for.
It does seem that they are louder. I think there is a lot of marketing speak when it comes to amp power and how that actually sounds. Most solid state amps don't deliver anywhere near their rated rms power to the speaker. Also, I think tube amps amplify the frequencies that sound louder to our ears and tend to track playing dynamics better. The science of it out to be out there somewhere. I just know that my 22 watts with two 6V6's is way louder than 100 solid state watts.
Keep it simple, but start w/a good foundation: Fender/Vox/Marshall all tube amp (essentially, a very rich clean tone). Add an overdrive pedal (or two), a pedal tuner, and a delay. If you want more options, add mod effects, wahs, tap tempo delays, etc.