Proper Drive removal

I need to switch out 2 drives (200GB and 250GB) and replace them by one 500GB.

Now the 200GB has a partition (i:\)that is part of my DRU1(other partition is the OS which is not part of the raid) and the entire 250GB drive (G:\)is also part of DRU1. 250GB has no data on it

For the 250GB a Remove from the DRU1 should be enough.

The 500GB will contain the 200GB partitions i:\ and i will extend the data partition over the remaining available space

So what would be the proper way to proceed to replace the 200GB with the 500GB to no screw up my current sync?

I was thinking of just cloning the 200GB to the 500GB and pop it back in and make sure the Data drive has the same drive letter.

Just copy the data to the new drive and use the advanced RAID reconfiguration feature.

For your case, it will be very simple.
After you copy the content of I:\ to the new drive and mount the new drive to I:\, the advanced reconfiguration syntax will be:
remove|DRU1|G:\

If you want to mount the new drive to a different drive letter, you will need to add a rename directive.
rename|DRU1|I:\|X:\
See the tooltip help on the UI section for that feature.

After that run an update operation to make sure everything is properly sync'ed up.

Thanks for the info, will give it a go this weekend