I wouldn't suspect the solar controller so much. It does happen where people dont get fully charged when using only solar. My Trimetric along with the Bogart SC2030 is set to return 112% RPC return percent charge. Along with setting the wet cell battery efficiency at about 94%.
I have used my toaster at 90 amp DC draw but not often. I think of GC2 as golf cart only and golf carts dont demand high amps as much as they demand long ru times. If I was going to attempt to pull 125 amps for our Kerig or micro I think I would go to AGM. We use the remote start for the generator/ coffee/micro/toaster etc. You may need an equalize. After running my four old wets very hard for 29 months they would fall on thier face. I didn't get into equalizing them and checking performance further because I went to a resi and six new GC2. Now these six 16 month old gc2 have recently dropped considerably one night I did an equalize and they seem to have doe better.
I have hit them with the genny for an hour or less in the evening lately so they wouldn't drop low enough for the inverter fall out. The voltage could be at 12.4 or so but when the tv, satellite, furnace, lights and frig are running I can be pulling 25+ amps. When something kicks on it can dip just enough for the invert sag to drop the satellite and tv. That means a reboot when DW is watching tv.
Wets are an excellent value but they do have limitations. I'm probably the guy who only gets the suggested 2 years or so out of them vs 6 or 7 because I cycle them to the limit often. They are always watered and usually not below 12.2 but...... I have also looked at other options but hesitated to go AGM or certainly lith because of at first not knowing if we would like RV'ing or find another second house or cabin etc. If I was full time I would surely have AGM and possibly lith. Since I'm rambling on I'll add more. I know that the rule of thumb is if you have say 200 AH of wets you can pull half of it. I have seen people say they could and stay above 12.2 and I have seen others say that it would be measured when taking the battery to 10.5. Well, 10.5 is never happening on my system and I find it more realistic to see 12.2 and be down around 120 or 140 ah.
I have been down about 160 or 170 but iirc it may have been around 12.1 or so. I dont see how I could pull 300 ah off this 630 ah bank. I have my Trimetric set to 500AH which makes the relationship between battery % full and the voltage more in line. I have also seen people say that the Trimetric needing to be reset from time to time and they didn't like it because of losing some history or lifetime amp count? Not sure on that as I'm no expert on Trimetric. It works for me to see volts, ah used, solar amps in, various item amp draw. Dont look at history much
Edit: Another example of wet performance is that I have a set of four sams 12 volt that are used lightly and recharged at around 15 to 15.1, I bought them in 2008 and replace as they die. Their ages are 2008, 2012, 2015, 2016. That's excellent for a cheap dual purpose battery but I can see how people might only get 2 years from a GC2 if running it hard. I pretty much put it in the fuel use category. 29 months for four gc2 was about $12.00 a month