Having turned into Goldilocks when it comes to rim widths, I can honestly say that 26-28mm is ideal for 2.3″ tyres personally. A 30mm internal pulls a 2.3″ Maxxis a bit too square in profile personally, and a 25mm internal width pinches a 2.35″ Schwalbe a little too much and it starts to lose its edge bite.
Been running 28mm internal E13 TRSr carbon rims mostly for the last 2 years, and they give a superb profile with either 2.3″ Maxxis or 2.35″ Schwalbe tyres. Currently using 26mm internal Stans Arch mk3 on my HT which are great with 2.3″ Maxxis fitted. Have used 30mm too which gave 2.35″ Schwalbe’s a good profile but did over stretch a 2.3″ Maxxis a little IMO.