Vueling's two frequent flier programmes: which one's best?

I am about to book a flight with Vueling and I got to the point where I need to decide which frequent flier programme do I wish to use: Vueling Punto or Iberia Plus?

It seems that, although, both Iberia Plus and BA's Executive Club use the same "currency", Avios, and they both belong to IAG, their frequent flier programmes, unlike, for example, Air France-KLM's Flying Blue, are still run separately.

I am a Vueling Punto member, although I have seldom used it, but I gave up with Iberia Plus and switched to British Airways' Executive Club instead...so it seems that for me the best option is to stick with Vueling Punto but I have made myself the following question:

Are there any specific advantages of being on Vueling Punto instead of being on Iberia Plus? I mean, if Iberia Plus lets you collect avios both on Vueling AND on other Oneworld airlines whereas the former only lets you collect miles on Vueling. What is the point of holding the Vueling Punto? or maybe the "Exchange rate" between punto and Avios is not that favourable?

Any frequent flier programme experts in the room?

What is going to happen to BMI Diamond Club miles after BA's acquisition?

As most of you might already be aware of, British airline BMI was sold by Lufthansa to its Oneworld competitor IAG (aka British Airways). Once the news was confirmed, one thought came to my mind: what happens with BMI's Diamond Club frequent flier miles?

As both airlines operated out of the UK, many frequent travelers were members of both British Airways' executive club and BMI's Diamond Club.

The truth is that BMI has moved fast to inform its Diamond Club members and in the last few days has sent a couple of messages providing updates...it looks like BMI Diamond Club cardholders are actually going to get a good deal and, whereas they will have only until the 31st of May to use their miles within  the Star Alliance group, the Diamond Club programme itself will continue to work as usual.

This is possibly the reason that BMI is still accepting applications for its Diamond Club programme while I am writing these lines:

I ignore if this "business as usual" will last for long, as Diamond Club members  are being invited to join British Airways' Executive Club programme. They will also be able to exchange miles into IAG's Avios at a rate of 1:1.

This is literally, an excerpt of BMI's Diamond Club notification email:

"As part of the transition of bmi into British Airways, from 1 May 2012 British Airways is inviting you, as a Diamond Club member, to also join the Executive Club at your equivalent tier status level. Diamond Club Gold customers will be invited to become Gold members of the Executive Club and Silver members to become Silver, which will be in addition to your Diamond Club membership. Further details will follow shortly."

Whereas it's not stated explicitly, I guess IAG's plan is to progressively transition all Diamond Club members to Executive Club. In any case, I think Diamond Club's members are getting quite a good deal and many of those that were on both programmes will be able to consolidate and advance their status within the programme really fast.