Deben entrance is usually pretty straightforward although if I recall correctly there were no leading marks apparent last year. Straight in and keep over to starboard of the channel as you get to the dirty great port hand marker usual does the trick! I'd agree that neither of the entrances is much fun in a blow although you are a hell of a lot safer in a RIB than trying it in a yacht or powercruiser imho!
You might be interested in a cruising weekend we (BIBOA) are running over the bank holiday weekend 4/5/6th May. Basically 3 days of cruising from SYH hopefully encompassing Southwold, Brightlingsea and the Deben/Walton Backwaters. If you'd be interested then drop me a line for details. firstname.lastname@example.org