Then you have a situation where interest only is less than the rent, you can't be evicted assuming you make the payments, unlike a tenant. 25years is a long time...
This is what my missus does (only her names on the mortgage). Works for us as we intend to have moved out well before 25 years is up.
The advantage of renting over either mortgage option is flexibility, a friend just moved from one 2 bed house to another and they reckoned it cost them £10k by the time they'd paid the banks, solicitors, agents, taxes etc, and they'd only lived there for 3 years!
TBH I don't get the whole "must buy a house" philosophy this country has, why? So you can spend 25 years paying for it, followed by 20 years of being smug to people still paying for them, followed by having to sell it to fund 10 years of paying someone else to wipe your arse for you?
Having said that our next house will probably have to be a repayment mortgage.
Renting = paying another mans mortgage.
Paying a mortgage = paying the bankers coke and Porsche habit.