I think you guys do not understand the Speedrent proposition 

what does no deposit mean ?
- Speedrent guarantees you 2 months rental if the tenant does not pay up
- Speedrent charges the tenant 1 mth rental upon expiry of tenancy, equivalent to the 0.5 mth deposit that you will return to tenant, upon expiry of tenancy
- Speedrent will pay you every month, not the tenant - then Speedrent in return will charge the tenant for the rental monthly

Speedrent charges a fee for this service.

You are not obligated to take in any Tom, Dick and Harry tenant. At the end of the day, it is still the owner's prerogative to choose and select the tenant that approaches you via Speedrent.
Speedrent is a facilitator of the 2 parties, by using Speedrent, you save on 1 month's deposit to agents. (which to me works out to be almost or slightly more than the 10% fee Speedrent charges for the service)
No I do not work for Speedrent, but I believe they are a disrupter, along the line of Uber and Airbnb.
I'm just a big fan of their business model. Whether they succeed or not, it's a big question - as they do assume a certain amount of credit risk.
For the landlord, your risk is as good as renting to any tenant on the street.  You don't like the profile, you don't like the person, you don't have to rent.

On the question of an agent subletting it out, you as Landlord - do sign an agreement with the tenant on their obligation and do's and dont's of the tenant.

So I suggest you guys do some homework first, before crying hoohaaa over the "no deposit" proposition.
Please lah,  go study the model before crying foul. geeesh