Sorry guys, bit slow to respond. Been away to Exmoor Bongo mountain biking.
Man, 1/2 a gallon of beer, a glass of port, 1/2 a bottle of red and 3am bed time do not make for a good start to the next day. At least the Bongo was comfy!
Scanner, I like GHDs . They cost a little more but I'm worth it.
BDC and DBO if you're not blowing fuses you don't need to upgrade anything. There is nothing wrong with the set up you have except that it will blow fuses if you discharge your battery too much. If on rare occations you do blow a fuse, do what Mike does or charge up from the mains.
The only reason I originally used the lower rated kit was because I wanted to keep the costs sensible. At the time Martin wasn't making his 100A relays and commerically available VSRs are around £65.
When I fitted my split charging system Martin had started making looms or VSRs. If he had I would have used one because they are simple and imo good value. That's why I always point people in his direction now instead of suggesting they follow my original instructions.