I was in the same situation about 8 months ago. I went from a 17' Triton to a 18.5' Ranger. The difference was very noticeable to me; however, there are several variables in the mix as others have mentioned. Manufacturer, engine size on each (my 18.5' has a 175 whereas now most only have 150), your overall comfort with fishing in the wind/wake, how often you would actually go out in 20-25+ mph, etc. From the discussions I had when I was doing research, nobody ever regretted getting a bigger boat assuming you can afford it and have a place to store it.
Yamaha 175 HPDI