I've never heard of such a thing, but I can tell you pine needle mulch doesn't fall down the cliff. I've used that on the side of my road, which is only about 4' high, but steep enough regular mulch ends up in what would be gutters if my country road had them.

This is pure supposition, but it seems to me that if nothing else, leaves have less carbon mass than wood and therefore have more concentrations of nutrients/minerals per volume and mass than wood. And, as ellatiarella brings out, the decomp rate of leaves is much faster than wood. I agree that while decomposed woody material has benefits ( I use a lot of it myself,) leaves are preferable for both nutrients and turn around time for reentering the soil web. In fact, even in nature the slow decomp of wood benefits carbon sequestration, while the faster decomp of leaves (and more delicate biomass - including grasses and other less durable plant growth) is much more responsible for playing a role in the creation of creating nutrient-rich topsoil. That said... it's also true that any nutrient benefits of composts and mulches are long-term at best. They are not, in themselves, a replacement for situations where fertilizers are needed for optimum plant health.

The plants are not biennial the individual canes are effectively biennial, as in deteriorating after fruiting. But there are two different growth modes within that general pattern: the conventional mode where a new cane grows its main stem the first year, then produces side branches that flower and fruit the second year. After which it can be removed. And then there is the second, so called everbearing mode where the first year canes go ahead and produce flowering side branches in the upper part of the cane that first year. Followed the second year by additional side branches appearing and another round of fruiting taking place. 'Heritage' is the flagship cultivar for those kinds that fall within the everbearing category. With it having been suggested that this one is sufficiently vigorous that if the second year crop is not needed 'Heritage' can even be managed by mowing it off with a lawn mower set on high each autumn. Thereby making trellising and selective pruning unnecessary.

I have a comment about weed seeds, or any unwanted seeds. I use a product called Preen, but there are others - they prevent the germination of seeds, but do NOT hurt plants already growing. So, obviously not something you use if you are hoping nearby plants will self seed. However, I have used it forever, and it works fantastically. I only mulch my roses once a year (right after pruning or trimming them, whenever that happens - in a warm climate I can do that most anytime). First I deal with the pruning or trimming, and remove any weeds or nearby ivy or bulbs which have crept too close to the base of the rose. Then, I water the rose well. Then, I sprinkle a handful or two of Osmocote on the soil under the rose out to the drip line of the rose (my theory is that this will provide nitrogen while the compost is decomposing further, and both of them will feed the rose). Then, I put a layer of at least 3 inches of home made compost my DH makes on top of the soil out to the drip line, of course keeping at least 3-4 inches away from the base of the rose. Then I sprinkle Preen or some similar product all over the top of the compost, and (very important) water it in. Voila - done for the year. By the time a year has gone by, the compost has fed the rose and turned into soil, so I repeat the process. I also use Preen on bare soil if, say, an area has just been weeded and is all clean. It has worked like a charm always, and although nothing is 100%, it reduces the amount of new weeds by certainly 95%. Regarding my DH's compost. Our property is a city lot of only 1/3rd of an acre, but we have a lot of mature trees, most of which are deciduous. He makes it from grass clippings and shredded leaves (the small leaves don't need to be shredded - just the large oak leaves) from the trees in a very large sort of raised bed place he built in the back of the lot, which he can leave open to the rain, or cover with a thick plastic sheet to let the compost rot and get hot underneath. Then when the Fall cleanup has produce MORE leaves, etc, he bags up last years crop which has sat for 12 months already, and puts it in those huge strong black garbage bags - it usually makes 7-8 of them. It stays in those bags until eventually one by one the bags are dumped into a medium sized plastic garbage can which lives on my wheeled garden trolly, so it is easy to wheel it to where I am working in the garden. One crop lasts me about 12 months. So, there is always one bagged crop aging further, and one new crop in the compost raised bed, while the trees grow another crop of leaves... I like it because, after sitting for 12-24 months it is the darkest, most wonderful compost, and the roses love it. Also free - what's not to like? Jackie