One house, one title but divided into two units - pros and cons?

Particularly interested in the pros and cons as an investment compared with a conventional house. Yield is expected to come in at 7% or better.
Long term would you expect its capital growth to be similar to surrounding properties? I understand that a property like this would be more difficult to sell, though am looking at it as a long term hold.
Am also trying to determine what kind of premium it is worth paying to get a higher yielding investment.
Ideally want it at price of a similar regular house, but have to figure out if a premium of say 5% - 10% would still be a reasonable deal.

Don't suppose anyone has a nifty formula that would help? :p

Have read numerous threads covering legalities, and practical points regarding mail, power and rubbish bins etc and think I am up to speed with those issues.
How much would it cost to convert back into a single house?

If it's a relatively cheap and easy job then if the property was worth less than its neighbours you could rework it prior to sale.
Okay, so if it can be reconfigured without too much expense, then as a long term hold you come out with average capital gain, or better depending on whether another investor wants to buy it because of the yield.

Is it worth paying more up front for the increased return though? Say you get $200 per week more rent than if it wasn't divided, wondering what that would be worth in terms higher purchase price - $20K ... $30K....$40k....

I'm thinking that after four years of the higher yield, you have kind of 'paid off' the premium and then the extra yield is cream from then on.