I don't grow these, BUT I don't think it's 2 different variations, likelier it's new growth, juvenile, vs. adult growth. Example: In Sans plants, we know that juvenile leaves can look completely different from their parents, dramatically so. Since no one has responded so far, I thought I'd try. Post back in a month w/an update pls & let's see what develops.

https://www.ebay.com/itm/Rhipsalis-Clavata-Jungle-Cactus-epiphyllum-cacti-exotic-succulent-plant/333461507590?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908105057%26meid%3D4ef4c42e6cc14601bfb650f86c428890%26pid%3D100675%26rk%3D3%26rkt%3D15%26sd%3D193266682710%26itm%3D333461507590%26pmt%3D0%26noa%3D1%26pg%3D2380057&_trksid=p2380057.c100675.m4236&_trkparms=pageci%3Aa38a3155-30e8-11ea-ba46-74dbd1801ebb%7Cparentrq%3A7d816f0016f0a12931171514ff917e2c%7Ciid%3A1

Oh man I hate to be a Debbie Downer, but I‘m pretty sure that could be mealies. The mealy bugs I usually see don’t really move at all. Makes them super easy to kill. Sometimes I will just see white cotton fluff and never a bug. Exactly what I see on your cactus. It’s kind of weird tbh because I know there are bugs somewhere laying these fluffy egg sacs. Take some of the white fluff you’re worried about and rub it in between your fingers, if it’s bugs they will leave behind an orange color on your finger. The one I circled red really doesn’t look right to me. See how they’re hanging out in the joints? That is very stereotypical of mealy bugs. This pic of a Rhipsalis from DangerGarden is what ”normal” white fluffiness looks like. Rhipsalis hadrosoma pretty much doesn’t have bristles, very different from your Rhipsalis. Pic R. hadrosoma from Google.

Hey Karen, Sorry it seems like I couldn't see a good chunk of your last post when I first responded or maybe I forgot to scroll down. 5-1-1 mix is 5 parts pine bark (fairly fine like the reptibark you use, 2-10mm range), 1 part pumice or turface or some other porous rock (I use pumice), and 1 part peat. Just recently I made the mix with slightly larger bark fines (5-15mm), so we will see if that results in better growth. Like you say, epiphytic cacti like fast draining mixes and are used to very loose soil/organic matter. I'm not intent at all on removing the peat from roots dry. In fact, the last plant I potted up I removed all of the peat wet as you've suggested, but I did water it in straight away. I think your suggestion to remove the peat with water and then wait a few days to water the plant in is a good idea, I will definitely try that out in the future. Some of the plants I've ordered via the internet have the root ball in plastic bags so they have to be potted up immediately. As far as being confident that my mix is better than straight peat from the nursery, I'm fairly certain it is. Besides the fact that peat is overly water-retentive for these plants, it typically comes fairly compacted from the nursery meaning there is no structure or air gaps in the soil. Using a 5-1-1 type mix allows me to water more frequently (good for root health and gas exchange) and my established plants are growing really well. Thinking about the issue carefully I think that perhaps the combination of root loss when getting rid of the peat, coupled with perhaps potting up into too much soil (given the drastically reduced root ball) might be the problem. I've noticed that when I repot plants that are actually composed of many different cuttings shoved in the same pot, the newly repotted individual cuttings are more prone to this problem. In contrast I've had less issues potting up larger plants composed of 1-2 cuttings with much larger root balls, even after removing the peat. I live in Barcelona. The botanic garden is a bit of a haul to get to, but I think I know a grower or two that I can talk to. Regarding twisting off stems as you say, it might also depend on the species. For example my R. grandiflora, pachyptera, and paradoxa all have stem segments that narrow down where they attach to the stem. Thus the resulting wound is pretty small, especially if the segment you twist off is already loose. In contrast when you cut an epi right across the middle of the stem the wound is quite large and I would be very suprised if it did not rot were you to immediately pot it up.