They're both all alloy, so they WILL wear through gas cutting, particularly the second baffle. These can be replaced at a cost of about £17 each but don't actually need replacing until they have virtually worn down to nothing. I spoke to Jacksons at length about this recently - on rifles such as .270 you need to consider the baffles on all alloy moderators as wear items that will need replacing after a time. The actual length of time will depend on the calibre, load and usage. If you can't strip the mod' due to bonded threads, send it back to Jacksons and they'll do it.
On balance, that's a price I'm prepared to pay for a moderator that transforms the weight and balance of my favourite rifle. If not, choose a non- wear model instead. By the way, I can't see any difference between the CMM4 and the Roedale, or am I missing something?
A.