For the first; I'd always argue that test standards are far more important than hours anyhow.
Ah, "competence-based". You're sounding more like FCL.008 every line.
So, let's change the hours to 5 / 5 / 5 / 10.
It still doesn't answer the question of why you need part (4). Shouldn't that be part of the ATPL?
For the second, surely the benefit of such a system is that a pilot can choose for themselves from (1)+(2), (1)+(3) or (1)+(2)+(3) without anybody else dictating what they should want.
I think (1)+(3) might be workable, provided the privileges were never exercised outside the UK, but the ability to fly "in the system" offers a huge benefit at little cost in training. The best kept secret in UK IFR appears to be that flying in controlled airspace is much easier (and therefore safer) than messing around outside it. But, perhaps understandably, only those with IRs appear to appreciate the difference.