For £70 per person per leg I would regard this as a good deal, I would go for it. Particularly if you can find flights where the midhaul 321 goes to FCO, which it does from time to time - this has flat bed seating. Admittedly it's difficult to confirm this if your travel is some time away - it's apt to change closer in. But particularly if you don't have status and you would otherwise be on one checked bag per person, this would quite a good deal to my mind. Fast Track is perhaps worth having, but it's only a few minutes. The 3 lounges available to you in LHR T5 are certainly a good feature here.

What this thread will illustrate is that there are quite distinct groups of people out there: there are travellers like me who would generally tend to book CE for anything other than short hops, and there are those who not normally pay anything more than a token amount extra for it. I guess there will be a middle ground of pragmatists too, who would perhaps book CE after a difficult week away or if they can get row 1 or whatever. No group is wrong or right, but at least you can see the arguments for and against.