Have you just not used Alto or you would not use Alto...
I have one of the 12 channel Zephyr's, which I bought to save having to drag the whole rack out with the small acoustic band I play in, and I have to say that it sounds great. It has built-in effects, which are pretty good, and for £100 the build quality is superb. The pre's aren't bad, although they're never going to set the world alight, but at least they don't suffer from the daft gain structure you find on the Mackie CFX's.
I haven't used/heard any of the higher end Alto kit, but if it's in the same range of quality as my Zephyr then I'd say it's probably worth auditioning. Having said that, £300-£400 will get you a very nice desk from a well known manufacturer, so it's up to you whether you'd want to take the risk or not.