I didn't look deep into the comparisons. I mainly looked at retrieve and line capacities. Going from a 5500 to a 6500 wouldn't be a big difference on the base models. 6500 C4 would be a huge jump. I haven't looked at the C3s.
Ad we're going to have to agree to disagree about bearings.....
I've surf fished and distance cast competitively for the past 25 years. I also own a custom rod and reel repair business, specializing in performance modifications on Abu reels for the surf fishing and casting communities.
My Abu arsenal:
7500C3CT
7500CT Big Game
6500CT Mag Elite
6500C3CT Chrome Rockets x 2
7000C3 x 2
Ultra Mag XL II x 2
All Swedish Made (brass side plates). All highly modified with bearing, gear and drag modifications for improved performance or to suit a particular application.
You can't compare reels using line capacities and retrieve rates while ignoring the drag capacity and gear ratio. Your huge jump from the base model to the C4 is mostly marketing hype. Balancing the spool and tweaking the bearing shaft of a C3 will give better results. My Mag Elite will only
free spool for roughly 90 seconds...lol. Try that with all the friction generated by a C4
C = Spool with integral shaft. 1-bushing and 1- bearing, mounted in side plates
C3 = 7000 series...Spool with integral shaft....bearings (2) mounted in side plates. 6500series..Spool and separate shaft. Bearings (2) in spool.
C4= Spool and separate shaft. Bearings (2) in spool. Nylon bushing on the one end of the worm gear (level wind assembly) replaced with a very small bearing that quickly gums up and binds.
FWIW: You can buy a modification kit to replace both the bushing and non-rated bearing with ABEC 7 bearings but require very regular maintenance. Once a year doesn't get it here.
Be aware there are different version of a particular model. Abu builds model specific reels for a number of "big box store customers.It might say 6500 on the reel, but it's the part number that defines the reel. My Abu parts book list over 125 different version of the 6500 reel alone.