I've used all these saws (362 only briefly). And I own a 346, 562 and 385.
The 45-50cc saws are perfect for this use. If you think a 16" will be ok then the 241 is very nice and you stay in the stihl family, if 18" is a must then the 261 is the go. If you are prepared to go husky - a ported 550 from Terry landrum is a killer deal and an amazing saw, less money is a standard 545 from him and it is a good option. Ordering parts online is no big deal - and it's no different time wise as most local dealers don't seem to carry whatever you want on the shelf.
I use my 50cc saw more than anything else (actually 45cc as it's an oe 346), the extra weight of the 562 is noticeable and while it is the perfect saw for felling and topping up to 20" trees I believe you need a lot of this work to justify anything between 50cc and 70cc. (I do a lot of feral tree control, and wander around the scrub with only one saw, either 346 or 562).
For firewood collection you tend to drive to the tree, so having 2 saws with you is practical - and having a bigger gap between them makes sense.
For my 2c - option 1 is a wicked work saw ported 550, option 2 is 545 or 241 with a 16" bar (check Terry's pricing on a 545 vs a 241 from your stihl dealer), option 3 is a 261.
If you end up with a ported 550 or 261, be prepared to use your 441 a whole lot less!!!!