I'm currently running 175mg/week of pharma test cyp (25mg daily injections) and about a month ago I added 100mg/week of deca (25mg s, m, w, f). So far I feel great. I've always been a low-dose guy though...mostly because I'm 56 (almost 57) now and I'm trying to get/keep an edge in my training while trying to be as safe/healthy as possible.
Here's what I've noticed with this current combo. Keep in mind I haven't done any blood work recently so this is just how I'm feeling and what I'm observing. I wake up every morning with a solid erection...gotta be happy about that at my age!

My libido is "on point" for a guy who's been married for almost 33 years! My wife and I get after it 2-3 times a week which works well for us. ZERO deca dick and one interesting thing I've noticed is my stamina is through the roof!! Also, my loads are bigger than normal. Have no idea if this is due to the addition of the deca or not. All I know is the stamina and bigger loads appeared a couple weeks into the addition of the deca.
On the training side, my sessions have been great! Been utilizing a 5-day/week approach...Monday is upper, Tuesday is lower, Wednesday off, Thursday upper 2, Friday lower 2, Saturday is xtra delts/arms. Strength is definitely up across the board...especially on pressing movements and delt/arms pumps are fun.
Anyway, I run a TRT dose of pharma test cyp year-round and then add in 8-10 week cycles of lower-dose different compounds here and there for fun and to see what happens. This addition of 100mg/week of deca has been pretty fun so far.