I still need to confirm the maths, but I believe a combination of a regular saver, not reinvesting payments through zopa, and a monthly interest account may currently bring better value.
Regular saver - 8% before tax - with no bad debt risk, and FCCS protection
Instant access - 2.8% monthly interest ISA - again no bad debt risk, and FCCS protection
The main question would be - do you make use of the rapid return, and lose 1%, simply attempt to remove your investment in zopa over the year, and is it worth the effort for the extra security and would it increase your return?
Lets look at it this way... Lets say you are able to take out £200 from zopa a month, and leave it in the ISA until the regular saver is available.
For ease of calculations, lets exclude tax, as you are also liable for tax on income from ZOPA, so its a moot point comparing the two.
£200 invested into the 8% regular saver returns £89.99 in interest. Lets also say you have an average of £200 in your isa per month. That returns £5.67 in interest.
Your total return from ISA and regular saver is then £95.66 for the year.
Now over the year, you have an average of (£200*12/2) £1200 of this money in ZOPA. Zopa states an average return of 5.5% after bad debt etc. This would return £67.69 annually, although this figure could be more or less dependant on bad debt.
So in theory, you would be better of taking advantage of regular savers, than ZOPA.
Have I done my calculations right, or am I missing something?