Raid5 and LVM setup choices ...

[H1N1]

I would like some comments on possible set up options.

In short, I have raid5 setup with 3 disks at the moment with LVM on the top.
I am planning to add another disk (just one at the moment).
The total number of internal bays is 6 so I'll add one disk now and two later.

Question. With efficiency and speed in mind what would be the best option out of two below?

1. Add this one disk to the existing md0 so I have 4disks -> md0 -> LVM with the future setup as 6 disks -> md0 -> LVM

2. Fill the remaining 3 bays at once with 3 additional disks and create second md device so I have
3 disks -> md0 \
---------------------------> LVM
3 disks -> md1 /

I realise that with the second option I lose twice as much drive space to parity but I am interested more in speed.
With the second options I can get LVM to stripe across two md devices. Would it be speedier then the first option?

Thanks

[b2bwild]

I think 2nd would be a good option.

Having more number of arrays, decreases the probability of major failure.