Lots of guys had issues with SD, but in all fairness, it was not all SD's fault. There was a LOT of shit SD out there, which was poorly manufactured and contained either different isomers of the drug or various pollutants. There is no doubt that some of the available brands did NOT contain pure SD. Pure SD was much less likely to make people feel like shit than the pure versions. I experienced this myself many times...and few people have more experience with SD than myself, with more than 20 cycles under my belt.. Pure SD makes you big, hard, and dry, and very strong. Some poilluted version caused water retention and made guys feel horrible. As far as how it affected BP, it varies. Some guys had issues and others didn't, but the polluted versions which caused water retention were much more likely to cause BP issues than pure versions of the drug.
As far as M-sten goes, it is much less prone to side effects than SD is, from a "how do you feel" perspective. In terms of the kidneys, what many people don't understand is that steroids themselves do not cause much kidney stress. They can cause some direct stress, but any kidney issues which develop are primarily due to high blood pressure--a potential, indirect effect of AAS use. M-sten is not known for being problematic in this regard, although any AAS can technically increase BP. Personal response also plays a big role in whyether or not a steroid will elevate BP. M-sten seems to be about average in terms of BP issues. Personally, it does not increase my BP at all, or if it does it is only by a few points, literally.
If BP is an issue for you with steroids in general, there are many things you can do to control it. Adbanced Cycle Support is a GREAT products for managing BP. It contains multiple clinically validated compounds, at clinical dosages, for controlling BP. Hawthorne is one of the best, which is also included in ASC. Of course, ACS alos contains multiple liver detoxifying compounds, which again, have been clinically validated. many guys have used drugs like M-sten with ASC and both BP and liver enzymes experienced little to no elevation at all--that is impressive. I always use cycle support. There just isn't a good reason not to, especially for those guys who regularly use AAS.
So, the bottom line is that M-sten does not increase BP more than average, with many people experiencing little to no increase. For those that are more prone to experiencing BP issues, the inclusion of ACS can largely eliminate that problem. I think you would really like it...and I can gaurantee that your gains would far surpass what you would achieve with Anavar, Masteron, or Winstrol. A 6 week cycle at 30 mg daily is a very solid cycle. Personally, I would run it the last 6 weeks of the cycle, which will enable you to finish your cycle looking your very best, but you can also kick of your cycle with it, as well. However, keep in mind that if you begin with it for the first 6 weeks, you will likely notice a decrease in muscle fullness, overall size, and possibly even strength levels after you go off. You won't lose any actual muscle fiber because you will continue using other steroids, but there will be a little lag period were you probably won't look as good for a couple weeks. That's because the drug produced powerful effects, so naturally, when you stop taking it those effects go away.