I am taking T4 & Clen for a cutting cycle with M TRN and Zol at the moment.
I've never taken T3 so can't compare but it is working very well now. It took a long while to kick in though, for 9 days I did'nt feel any different dispite ramping up from 1 - 6 tablets over 6 days. I even made a post on here asking for any experiences with T4 as I was beggining to think my tablets were bunk!
Soon after day 9 I began to notice increased sweating and flushed feeling which increased in intensity over the the following couple of days, so much so actually that I dropped the dose back down to 5 tablets (500mcg) which I have been on for since that point. I believe this may be one of the main differences in that T4 takes a while to accumulate to an effective level in the body.
Once I realised it had fully kicked in, I threw some clen into the mix which has been working very well, dropped 8 pounds in the last 2 weeks with no loss of strength. Keeping clen dose low though as the T4 seems to really amplify the effect!
The only real side I have experienced from T4 is excessive sweating and flushed face at times, not noticed racing heart or anything else concerning.