Well, I feel I can make a valid contribution here as I play in a covers band and I use a H&K Switchblade. I wrote a review of the Switchblade that you may have read but to summarise, there are pros and cons. The tone isn't as warm and natural as some of the really good, traditional valve amps like a really good Marshall but neither is it bad. It is versatile and a lot more versatile than I need. Of 32 banks of sounds available, I only use three of them and each bank has a Clean, Crunch, high gain rhythm and lead sound available. For two of the banks it's only to change the voicing from British to American and the third bank is only because a particular song we play needs a particular set of effects. Some things I have discovered about it while I've been using it:
1) While the Lead channel is supposed to have a 'British' voicing and the Ultra channel has an 'American' voicing, the bottom line is that they all have a modern feel to them. The distortion is grittier than a Marshall so you can really get it to 'crackle' in a very aggressive way if you want to but it can also be tamed. It's not like a modeling amp because there is no attempt to slavishly duplicate another manufacturer's sound. The Lead channel certainly gives a strong nod towards Marshalls but the tone is still H&K.
2) There are a lot of ways to tweak the sound on a Switchblade because you have EQ, gain, presence, reberb and effects at your disposal and they can all make a serious difference so spending time with it is essential. Sure, it can sound awful, but there are also some really good sounds in there.
3) Newer models come with factory presets stored into the first 16 banks and these can be very useful when understanding the amp. I'm not suggesting they're perfect but they do give you a really good starting point when creating your own tones and I've found that with many of them, only minor tweaking is required. The Gary Moore preset for example was almost spot on right out of the box and I'll be using it next week when the band tries 'Empty Rooms'. If nothing else, the factory presets help you to understand how the amp's controls work quite quickly.
4) For what it is and the quality it is (they're very well built), I think they're priced quite well and they're certainly well priced if you consider what you save on effects (and space). I sold my old amp to help fund the purchase of this one but by the time I'd also sold my distortion, overdrive, chorus, delay and boost pedals and changed to a smaller pedalboard, I actually made a small profit on the whole thing :D
5) For the first time in my guitar playing life, I am completely GAS free. Are there better amps available? Yes, obviously there are but for what I use mine for, it's absolutely perfect and it's bloody loud. I've done two gigs with it now and I haven't been able to get it past 2 yet!
If you want to spend more money then I found the JVM to be really good. It had some great tones and lots of flexibility but was also more expensive and didn't have the effects built in. I tried the Laney VH100R after I'd already bought the Switchblade and was also impressed with that but I found it to have a grittiness to the distortion that was closer to the Switchblade than the Marshall and an amp that big was simply overkill. I've moved away from big amps with a 4X12 cabinet as it takes up too much room fo no real gain. I put my Switchblade combo on an amp stand so it projects better and mic it if required and I need nothing else at all.