I've still got a pair of MK1 422a's that are going strong after 8 years and I very rarely see the limit lights on them

On the Alto's.... I picked up a pair of TS212's (because they were white) and I'm pleasantly surprised at how robust they are, how they sound and how capable they are (in terms of output). That said, I hired them out last NYE and they came back with a fried tweeter so you do have to be very careful how hard you push them. I'm not planning on using them without a sub for anything that I think might stress them (that's anything more than 40-50 people in a small venue). As Justin has said though, for £600 notes - they're fine.

RCF312's/315's are good for the money and will be a good, reliable PA. FBT also do a strong entry level range of 12" cabs for around the same money (either the J series or X-Lite, both for around the £700-£800 mark). The advice everyone has given so far here is solid, listen before you buy and avoid eBay packages (they're generally full of tat that'll make you want to throw it away within a few weeks).