I would warn, I bought a 43cm ski for my first boat, only because it was dirt cheap and I made money upon selling it, and I knew it was an elite level ski that I would swim a lot in, but I bought it anyways.
I swam a lot. Like, 22 out of 25 times out with it, and I have pretty decent natural balance (enough to stay upright in intermediate boats with no specific training). I strongly do not recommend going from a 71cm flat water kayak to anything skinnier than 48cm. as soon an you go 1 micron skinnier than 48cm, you quickly go from "a 48cm intermediate boat that almost anyone could paddle after a couple months of practice" to "a 43cm elite boat that will take many months of 4+ times per week of paddling, dedication to balance training, and a ton of swimming" before its fun to paddle.
I would highly encourage you to look for a ~48cm boat (mayyyybe as skinny as 46cm like the Stellar SEI or Nelo 550 at the absolute skinniest, but even that isnt my first recommendation). Resist the urge to buy an elite level boat. If I were you, i'd buy something between 48 and 52 cm wide depending on how aggressive of a step you want to take. 52cm you will master in no time and you can just focus on form training, 48cm will take a little bit of work but not unapproachable, 46cm will require some regular paddling to get comfortable in, <46cm will be no fun for quite a while (unless you're paddling nearly every day or are naturally gifted with balance)
Even a 52cm boat will feel like a rocket compared to the barge you currently have. Trust me, swimming every single paddle is no fun. Its fun to get thrown off, but it should happen on your terms (i.e. venturing out into bigger water), not flipping on flat water.
Other reasons to buy intermediate
-You can add seat pads to add instability if you get bored too quickly
-Poor form is developed from excessive instability, best to get good form in your muscle memory before you have to unlearn bad habits
-the resale value of intermediate boats is better than elite boats (because not many people can paddle elite boats!) and if you buy used you can often sell for the same price you bought
-If you paddle alone, a safety margin of stability is advisable
-Swimming occasionally is ok, but any of the elite paddlers will tell you "stability before ability"!
Off the top of my head, I think an SR, Zest, XT, V8 Pro, V10 Sport, Evo would all be a good starting point for you. If you feel aggressive an SEI or nelo 550 may be on the menu as well
Currently paddling a Kai Wa'a Vega Flex in Southern California's ocean waters
Past Boats: Epic V10g1, Stellar SRg1, Fenn XTg1, Swordfish S
"When you've done something right, they wont know you've done anything at all"