Whats the matter with you! Glasgow to Sussex? I thought you Glaswegians were tough...EASY!!!!

OK, I get your point!
I only drive a pair of speakers for the average gig for up to 120 guests from a Numark Dimension 4 amp. If it is a marquee, I will add a pair to the amp - ie 4 speakers.
My speakers are all 8 ohm, in your case, they are 4 ohm, so you really should not have more than one pair per amp.
For bigger gigs, I add speakers and amps.... I also have a couple of 500W bass bins whick I use for dance music oriented gigs
If you have not bought them yet, ask to hire them with a suitable amp from the retailer selling them. If you want to buy, you should be able to get a refund on the hire if the chappie is reputable. All those years ago, I had earmarked £800 for a pair of Cerwin Vega 15" cabs, I hired a pair, the hirer called me back saying that they had failed and I would be better off getting the McGregors. He used these on his hire stock and never had a failure. I reluctantly gave them a try, and was so impressed, I bought a pair. I have not regretted the purchase, I even managed to by 4 more second hand a couple of years later.
There is another manufacturer you may wish to investigate: Deltec. They were at Plasa, and they make really good speakers for mobile use. They also use Eminence drivers which are highly respected.
Marky Marc will now come along and advise you to get a 10Gw JBL stack
Cheers,
Brian