There is no receiver vs integrated consistency.
I have or have owned: SX-650, SX-950, SX-1250, SX-1010, SA-7100, SA-9800, SA-9900.
First to compare the integrated: The 7100 was warm and lovely, but I wanted more power. The 9900 was harsh and had something very quickly fatiguing and non-musical about it, never liked its sound. The 9800 had power and musical quality that the 9900 never had, but never quite as nice as the 7100.
The receivers: SX-650 (2) were actually very good sounding. Were only repair projects for a friend, and I expected them to sound like crap, but they surprised me.
SX-1010 is IMO the best sounding of the group, followed by the 950 which is a little more detailed and less tube-like, but still very good musically. The 1250 is the 4-ohm powerhouse from Pioneer, has the power to punch hard with any speakers, but doesn't quite have the warmth of the 1010 or 950, ... but the differences are very slight and only evident on certain pieces of music.
So to say that one type of equipment or even one year-range is all the same is IMO not even close to correct. One only needs to look at at schematic to see that there are very few of the same component in (for example) an SX-950 vs an SX-1050. It does seem however that the general trend from SX-1010 (and the other 1975 receivers) to the SX-xx50 and then the SX-xx80 was less "warm" and trended toward a more technical sound, ... at least in my experience.
What was mentioned above regarding speakers is a huge consideration however. It is my opinion that my SA-9900 sounded like crap to me because my speakers that I ran with it (JBL 4312A, PSB Stratus Gold, Infinity IL-40, Yamaha NS-500M, Digifine SX-911) are my taste and have very accurate HF, where running it on perhaps a JBL L100 with the cone tweeter and less HF accuracy might not reveal a shrillness or higher harmonics. Just a theory.
So IMO they are all different, I have felt the same about the several Marantz 22xx/23xx receivers that I have owned, and it's pretty much impossible to decide what you'll like unless you take your music and your speakers to audition on the receiver/amp (which was much easier when they were all lined up new in the store).