I'd steer clear of sealed bids. In general, 2 beds do not get double the price of a 1 bed for a number of reasons. Labelling one's food in the fridge etc. so that those sharing with you don't scoff it while you're out, being one example. Also people, in general, share because they can't go it alone however much they might like to.
A one bed, on the otherhand, can be let to a singleton or a couple who have their privacy while each are paying a reasonable portion of the rent.
As to plenty of choice out there, it depends on the area. Just because people aren't qeueing around the block any more, it doesn't mean that a virtual queue is not forming via email, mobile and text! This was true in our own case. We made appointments for people to view and they each saw it alone. There were some people who felt they could say I'll get back to you, which they did in every case, but they were disappointed. The apartment was advertised and promised to someone within a couple of days. Signed, sealed and delivered within a week. I took my phone no. off Daft but left the ad up until the money hit my bank...ok I then forgot to take it off daft for a while and as I was only receiving emails, didn't realise it until I checked my mail!!
However, if you're covering the mortgage at the moment with 1650 on a D4 property, then I imagine it's an interest only mortgage or else you had a huge amount of capital to lay down. If you want to hold on to the apartment perhaps you could try to whittle the loan down, even slightly, to cover the latest interest hikes. One of the other alternatives out there for properties close to the city is, to rent it to a company who then sublets it to corporate tenants on a short term basis. You may be offered over 2k a month for this, depending on the calibre and location of the property. Cleaning bills and utilities are paid by you but you don't physically have to get the cleaners in. The company looks after it all. There are at least ten properties rented in this way in our apartment block. To the casual viewer and even the census the apartments look empty. In fact, corporate tenants occupy them on a one day a week/one weekend a month/ one week a month basis and their companies are charged an arm and a leg for it.
I would accept 1650 because you've already invested your time (interviewing tenants) and your money (adverising) already. Presumably this covers your mortgage, management fees and insurance. Lots of landlords are in it just for the capital appreciation although there are people out there who say that this boat may have sailed and is now simply cruising. However, they can't have it both ways..i.e. FTB stop buying and rents decreasing. If they stop buying, they still need somewhere to live/rent.
Good luck in your new venture.