V8 The first downside to the multifx is that the presets almost always suck - unless you have experienced the originals the sims/models are based on - it's challenging to find recognizable tones. How many of us know what a Marshall JTM800 or Fender Blackface sound like cranked to the full spinal tap?
Exactly. But what if you had a Marshall CODE? It only has 24 effects and 5 simultaneous ones though. You can switch them on or off with the footswitch or change preset banks and presets with the footswitch. I may be biased because I just bought one, but the amp/power-section/cab sims on the presets I tried sounded awesome.
V8 The second is you'll want to 'Get Another Amp' - something that has a full range speaker. Guitar amps/speakers colour the sound a lot, which you'll likely want to be doing in the multifx (if using the amp/speaker sims). In a pinch a bass amp will work, acoustic amp better and a pa might be best.
I agree fully on this. Playing songs from your phone through the aux in sounds really bad on electric guitar voiced speakers.
V8 All the while referring back to the basic/bypass'ed sound, trying to keep the basic patch and subsequent patches vol's similar so I don't get a big bump in volume when switching between patches.
That's the tricky bit right there - Balancing the volume differences while keeping the tone of that patch.