Increasing Tyre Size - Geax Saguaro TNT

It would be great to get some opinions on increasing tyre size - i currently use a Geax Saguaro TNT 2.0 on the rear and have been generally happy with the overall grip, wear etc - that being said this is in comparison to a crossmark 2.1. I use a Nevegal UST 2.1 on the front.

General blurb about the tyre is:
• Arrojo's natural evolution: same polyvalency and low rolling resistance. A tyre that nicely falls in between the Mezcal (dry, compact) and the Barro Mountain (wet, loose).
• Low rolling resistance thanks to the central uninterrupted knobs that enhance speed on compact ground;
• Aggressive and predictable tyre when cornering even on loose surfaces thanks to the Rails Designprofile optimized for dry and compact conditions;
• 2.00 size is ideal for XC application 2.20 just "blinking" at enduro/all mountain applications is better suited for marathon courses;
• Sizable air volume and Tuned Spring Rate Casing (phase 3.1) gives for a comfortable and, at the same time, aggressive tyre for different applications;
• Predictable and fast.
• TNT folding bead
• UST compatible

The 2.0 is a 50-559 (as compared to the 54-559 for the Nevegal and 56-559 for the 2.2) and i run about 35 psi pressure which feels mostly right for most part of the tracks i ride (Manly Dam, Oaks and Andersons, trips to Canberra, Glenrock) but there are times when i would like slightly more grip in techncial climbs eg the steps at Manly. I'll be doing the DW 100 and Angry Doctor 100 this year. Its worth noting that I am on the larger size and worry about running lower pressure in the smaller tyre i am currently using.

Will the benefits of going to a larger tyre with lower pressure outweigh the additional weight and drag of the large tyre - I realise this will be dependent on the tyre itself and i am not asking for a critique of the tyre (unless you have experience on both sizes) but just concentrating on the benefits of going to larger tyre for trails i ride?