Back in the 90's I had the OG 5150, been playing it a few years. Finally got my dream amp the SLO 100 with the depth mod. Long story short, I kept the 5150, sold the SLO. Several friends thought I was crazy as the SLO was top of the heap...the standard. Years later the 5150's would be the standard as well.
Both great amps, nobody will debate the build quality of the SLO but in the end, it's about what feels and sounds right to you the player. In my experience, I just much preferred the high gain tones of the OG 5150. It was everything I wanted in an amp at that time. I was spoiled with that amp for about 10 years.
The SLO is big and ballsy, sorta round in it's tone (to me) and to get that tighter high gain sound you're gonna have to run an OD. Back in the day I didn't even run an OD with the 5150, I could dial in my tone with the amp only. Btw/ I still don't run an OD into my amps, just not my thing. Personally, I'd go 6505's or the EVH's but that said, I'm a firm believer in trying something for yourself, that's really the only way to find out. Maybe you have that option, I don't know.
Good luck.