Without even reading the body
Even before I read the body of your post, my answer was “Yes.”
It’s always time to upgrade. The only question EVER is finances and storage. Otherwise, it’s time to upgrade. It’s the kayak version of “this boat’s not big enough” of the power-boaters.
lol
Storage isn’t a huge issue but finances are. Oh well, it’s too late now. I have listed my boat for 2 days and I already have someone coming by this weekend to look at it! It’s killing me as the local lakes/rivers finally have thawed enough to paddle! ARRGH! 
I’ll be waiting at least 3 more weeks until Canoecopia to even look at some kayaks and probably some time after that until I find a good used one. Pretty soon pool sessions aren’t going to be good enough. I’m a bargain hunter so if I see a good bargain on a boat, I may jump on it without testing every other boat out there. …I need to be more patient.
update on upgrading
As many of you predicted, I have gone and sold my boat. 
My kayak was bought a lot sooner than I anticipated so for now I am without a sea kayak. It’s funny though when I think about the process I went through in buying that boat. I must have researched for weeks trying to find an appropriate boat that I could grow into and use for years to come. I guess I just grew more quicker than I planned which is a good thing I guess. I have to keep reminding myself to not settle on an intermediate boat and go get a kayak that I can use and enjoy for when I someday reach “expert” status. Of course I have specific requirements in my next kayak which helps my search (16-18’ length, 22" or less width, low volume, low back deck, day hatch, skeg, fiberglass, vcp or kajaksport hatches, able to support 3 day kayak camping…). Basically I am now on the prowl for the prototypical “greenland/british kayak.” My top three as of right now are 1. Valley Pintail, 2. Impex Montauk, 3. Everything else (Avocet, Aquanaut, Anas Acuta, Nordkapp, Romany, Explorer, Greenlander Pro… So the fun part starts!
Schizo- you are advancing
so much faster than me. I'm still in the 14-16' range. I really want to look at the Prijon Calabria and Impex Montauk at Canoecopia. I felt very comfortable in the WS Tsunami 140. Sat in a bunch of Necky's at my dealer today, he just started carrying the line; they (Looksha Sport, Zoar Sport and even the smaller Manitou) all felt very good for my size which is about the same as yours. Philosophically, we are taking a different approach. I need to progressively ease into larger sizes while you are taking the "plunge". But then, you are a kid and I am in my "golden" years :). Thanks for the update and good luck. Perhaps we'll bump into each other in the Impex booth in Madison.
lol, yeah i’m still a “kid”
My paddling club never misses a chance to remind me of that! I do admit that being a young single person allows me the time/money/opportunity to more selfishly pursuit this sport. I don’t take that for granted as I know someday I will also be married with children. People progress at different speeds and it’s completely appropriate to match that progression with the appropriate boat. Heck, although we have differences, we both are looking at the same boat! The Impex Montauk seems suitable for a wide range of skills which makes it particularly appealing. My particular progression might be atypical but for those who are “addicted” as you and I seem to be, the destination and the appropriate boat is the same. I’ll be at Canoecopia all three days so if you see an asian kid hovering around the Impex booth, be sure to tap my shoulder and say hi!
I’ll certainly look for you
We have a weekend pass also but don’t know if we’ll be there for one, two or three days- it depends if my sister-in-law will watch the dog.
I’m about 5’9", 150 lbs., light brown hair, 54 years old, athletic and good looking :), intelligent :), funny :), sophisticated :), etc. :). Be Good.
Whee
I also tend to do mounds of research and comparison and theorize endlessly about what item would suit me best based on stats and reviews. That’s a lot of fun and I can’t discourage it. Just be prepared to throw all the theory out the window if it doesn’t match what you experience when you get to try the boats! Trust how they feel over what you’ve read.
I ended up buying a used plastic Avocet myself. I’m a beginner but adventurous, I guess, I wouldn’t call it tippy or difficult. Responsive is the word I’d use. I didn’t expect to be able to feel such a difference between kayaks as a rank beginner, but the Avocet was the only boat that felt like it’d do whatever I asked. Assuming I knew how to ask. (It was also the highest performance boat in my price range, I didn’t bother to try any fiberglass anything though it would have been fun.) In case you’re curious about the fit, I’m 5’9" with, I dunno, 36 inch hips and it’s a great fit. I would just need a little more padding on the hips for full control. Either my hips or the boat’s.
Z