Stiff denim and tight in the thigh area yes thats make the jeans really uncomfortable ! Had a pair that i sold i never worn them. When you have tried blended fabric with elasthan you cannot go back to cotton jeans.
stick to your normal size 28x30
tepphars have elasthan that make the jeans stretch out and if you can wear a 8X2 which denim is very stiff in 28 you wont have any dificulties to wear the tepphar with the same waist size.