Hello!
I've converted Cranberry to the junk schooner in 2015 for cruising on the lakes, canals and rivers - which are plenty around Ottawa. Works OK for our purposes.
Siren has a reputation of a tippy boat indeed, but with the low aspect junk rig and substantial "ballast" this junk schooner has a completely different personality.
The offset mast does not make any perceptible difference in heeling on a wrong tack. We don't have any ballast as such, but we use 45 lbs trolling motor as auxiliary, with 2 or 4 group U1 batteries in the bilge (about 10 kilos each), as well as the the cruising gear - including a couple of decent anchors.
The standard Siren is a bit on the tippy side even with 4'6" board down. In the shallow waters we sail we often put the board down just a foot or so - and the boat sails to windward without much drama. We sail her quite flat and reef often - but with the small junk sails it's very easy to do.
The sail area is about 92 + 55 sq.ft., the mast is offset to starboard, mast partner is bolted to the cabin bulkhead.
The compression post was removed - which made the tiny cabin of 17' cruiser more "spacious" .
Offset main mast allows for the offset boomkin - not interfering with the rudder, does not obstruct the companionway and somewhat increase the distance to the foremast - which is precious on 17' schooner.
The high balance (especially on the foresail) works OK for the tiny sails, and with the offset mast and boomkin helps to arrange two sails on a small boat. It's adjustable though.
For cruising I've replaced the 2 fixed windows of the Siren with 4 opening portlights, with mosquito netting. I did not modify the hatch.
The dinghy is Klymit LWD inflatable which weights about a kilo, and putting it in the lazyjacks is a very practical way to go through the locks on Rideau Canal. The windward performance with such a "sail" is somewhat lacking though :-)
I'll be glad to answer any questions but may be slow to reply as we plan to do some cruising this month.