Opinions / 2nd hand prices - Mackie SRM450 / SWA1501

I play in a few bands and our gigs tend to be weddings or pubs.
Usually 80 to 100 people - for which we use our own PA. Anything over
150 people and we hire in. Everything goes through the PA (no
backline) and we're not looking for concert level / hits you in the
chest volume levels. Weddings are usually ceilidhs and although we
don't sound like a folk band, we are definitely more rocky, we're not
looking to take people's ears off.

We're currently using 2 x Peavey HiSys2 powered by a Behringer EP2500
and run from a DDX3216 and it's working very well.

A friend of mine is about to sell a pair of Mackie SRM450's and a
Mackie SWA1501 bass bin. I'm attracted by the propect of using powered
speakers for simplicity and easier load in / setup. I'm also
interested in getting a better sound than the HiSys2s (15" + 1") give.
The kit has to put out vocals plus a whole range of instruments
including fiddle, mandolin, banjo, Scottish smallpipes, whistles as
well as acoustic guitars, electric guitars, bass guitar and drums.

So, my questions are:

Are these powered Mackie speakers significantly better than the
Peavey / Behringer combination we're using?

What would be a reasonable 2nd hand price for this kit (which is in
good order) in the UK? I'm guessing around =A3800 - given that their new
price is =A31,350.

Is there a better route for a similar amount of money.

I'd probably be trading in my extraneous gear to fund the new
purchase.

Cheers,
Steve W