I have been windsurfing for around a month or so no...probably about 15 hours on the water...can still only just tack but o.k to find my way back to starting point etc in most cases...the equipment I bought was a 160L JP Funster with a 460mast/7.5m Cam sail....I havn't actually used the mast/sail combination yet as I was told by many they are not great for newbies...tho I rigged it a few times and have had others use it....currently using a 430mast/5.2 non cammed sail.
Anyway..forecast for Sydney tomorrow is "light" with winds not expected to get over 15 knots......as it will be a slow one on the 5.2....would it be a good time to take out the larger sail to maximise my speed etc?
Pros/cons?
They are a little harder to rig(not that hard) and harder to water start. Since you'll be up hauling there won't be to much of a problem. Just give it a go and see what happens, if you don't like it come back and change. Just remember to bend your knees when up hauling as cam sails tend to be heavy when full of water.
When uphauling, lift the sail up only slighlty out of the water and pause for a few seconds before resuming the rest of the uphaul. Lets the water drain and sail becomes much easier to uphaul
If the sail and mast for the 7.5m are a good match, you should benefit from using them. The important bit is that they are compatible, as the wrong sail on the wrong mast may make the cams not work properly, and the sail may not sit correctly.
When I first started out, I had a 5.4m no cam sail and a 160L board. The instructor said not to bother getting anything else until I could plane in the footstraps with the 5.4m. I think he missed the fact that at 96kgs, a 5.4m wasn't going to do it for me.
I ignored the advice and bought a 7.5m cammed sail, and suddenly I had much more sailing time, and improved relatively rapidly. You do actually need to have some power in the sail. If the sail is too small you have nothing to pull against, and balancing is harder than if you have a bigger sail.
I would take out the 7.5m and give it a go. It will be less frustrating for you. If it gets too windy for you, just go back down to the 5.2m.
^^^^
Yeah I agree with that wise Formulala guy [}:)] 
Rig it up & have a go - you'll probably have a lot of fun in amongst the swearing
In my early stages I bought 7.8 cammed sail and tried it once,
only to realise that is almost impossible to up haul it at all.
If lucky then you will manage to up haul it few times that day and that will be most tiring exercise during whole sailing session.
So I left the sail resting for few years.
Few years later and the same sail become my favourite one for lighter winds: but two things changed -I do try not to drop it, if happen water start rather then up haul if possible.
So possibly worth to try now, and that could became benchmark for your progress on the water. The sooner you get comfortable with such powerful sail the sooner you feel real pro.
One for sure.After you do try this 7.5 next time you back to your 5.2 everything feels so easy 
smallest sail i have heard used by adults is 3.x
the largest is 12.x
so, 7.5 is smack in the middle
at 100 kilos/220 lbs i started with a 7-oh cambered sail
now my largest sail is 10-oh {cambered obviously}
cambered sails are a bit odd
they feel heavy when there is not enough wind
and they pull like heck when the winds pick up
i still prefer cambered over RAF in 7-oh and larger
the newer sails are easier to rig than back when i started
depending on your weight, a cambered 7.5 can be light or mid winds
i can uphaul my 10-oh, butt prefer to use my EZ uphaul for that
perhaps you can consider that as well
i no longer have any issues uphauling 8-oh
as they said - once you drop the smaller sail less often - GO FOR the cambered 7.5
if there are only 2 cambers like a free-race it is NOT that different from a RAF
no matter what - get on the water TOW and have FUN
joewindsurfer.com
There are cammed sails an there are cammed sails!
If you have a full on race sail with 4 cams it will me more difficult to rig an needs more technique to sail. However a free race sail with a couple of cams is not to far off a camless sail, just has more shape and rotation may be stiffer.
Give it a go. Get some advice on the beach from another cammed sail user on how to rig. Racier sails usually need a bit more downhaul, and if not set up right can feel heavy.
Good luck and have fun
Only use cammed sails when you are comfy blasting in straps and harness cammed sails are great my 7m rs racing gets me going in 12 knots and i can hold onto it in 28 just huge wind range
Thanks guys,
I rigged the sail and mast combination but couldnt get the top cam to sit correctly...so I derigged and went out with the 5.2...it was still fun but not enough breeze to really get any speed up.
Its a 3 cam North Sail with a NP XC35 460 mast...I know from other posts that the Norths only like to be rigged with the North masts but the seller had it rigged fine when he demoed it so it was something I was doing wrong..didnt want to risk breaking it so decided to derig. Will try again after further consultation. 
Will try again today (with the 5.2) as the breeze is expected to be pretty good later today.
yes, North is not near NP in the mast curve spectrum...
original owner somehow managed - ask him/her how to rig it well
also, sometimes just more downhaul helps...
