I have used a Slumberjack bag for over ten years. Bought as an overbag to extend my three season sack into winter conditions, I also use it alone as a summer bag. Given the very cheap price, I have been very pleased with its utility and durability.

The Super Guide looks pretty good, but bags from nearly all manufacturers tend to be not quite as warm nor quite as light as the catalog specs would indicate. Warmth is an individual thing. Some sleep warm, some sleep cold.

I would check REI's selection of bags from various mnufacturers, and also look at Backpacker magazine's product reviews of sleeping bags. They appear to be fairly straight evaluations.

I wouldn't hesitate to spend more. Bag, pack, and boots are the three most important itmes for the outdoorsman, and while I wouldn't necessarily buy the most expensive items in these categories, I wouldn't let price stop me from getting the very best for my circumstances. Everything else is just details.