I shouldnt answer this, because it'd come across as me co-ercing you. But many people keep more than two big plecs in a tank that size - as long as the filtration is good, and you're up for regular gravel vacs. I have two commons, a gold nugget, a rusty, a bristlenose and a flash plec in mine, granted - all babies, but there's room for them all when they grow up (but the BN and flash are probably moving into hubby's tank). Each fish is individual though, but as they're similar sizes, in this case - depending on what your common's like, I'd think it'd be fine. I'm only rehoming De Niro because he's going to squish my little ones at some point - he'd be fine with fish his own size. Probably a bit of a coward *lol*
Might be worth asking this on Plecofanatics too? Just for experiences and peace of mind?
Saying this - my group of plecs are the main attraction in my tank (there being three baby sevs and two baby festivums in there now - but not planning on any more upper level fish and one of those sevs might need a new home in the future) - and it depends on what else is in there and what the filtration is like. I'm planning on a second FX5 just to keep it crystal clear. That's a bit over the top but I will have 4-6 plecs in there rather than just two, one of which is a species which eats lots of bogwood and therefore poos sawdust (rusty) and is already making tonnes of mess and he's only half grown.
Eeeh heck, ignore my whole post as it sounds like I'm pushing you to take him - truth is it's up to you, and it'd be worth asking on Plecofanatics to see what they think.
