First, realize you're talking about an 8" woofer handling midbass duty. Now realize, you can't compare the JTR 8" speaker to a mainstream brands 6.5". This isn't because JTR uses some special speaker technology, nope, that's not it. The reason is that many brands have 3.5, 4, 5.5, or 6.5 speakers handling midbass duty and some even go lower to say 60 Hz. But with their speakers lower sensitivity, they won't play as loud or won't be as dynamic as the JTRs. It isn't due to technology, it's due to philosophy. Jeff and JTR started in the pro audio realm, which requires speakers to play louder to handle large venues.
To continue, let's stop talking about the 228 as the 212 will help me make my point easier but the same applies to the 228. So why does Jeff use not 1 but 2 12" midbass speakers when many companies would be happy to have a 12" sub in their speakers. The compression driver in the 212 is so efficient that normal speakers can't keep up. So to get the midbass region to be strong enough to keep up with the 212s compression driver, he ended up having to go with not 1 but a pair of 12" woofers. But since Jeff's criteria is for sensitive, loud, dynamic sound, he designed the 212s to play down to 60-70hz loudly whereas most companies would have designed their speakers to play low with a pair of 12" woofers. The same applies to the 228 but since that compression driver isn't as sensitive, he could get away with a pair of 8" woofers to play down to 80Hz as he wanted.
One other thing I'll say is that JTR speakers meet and likely exceed their specs even at loud volumes. No question in my mind if Jeff says a speaker will do X, it will do X and do it louder than just about any other normal speaker on the planet...even with a decent receiver.
I give you all this background because only you can determine if the 228 will meet your needs. I would assume the 228 would meet your midbass needs but neither one of us will know until you get the speakers in your room. I went with 212HT-LPs, partially because I didn't want to have any doubt in the back of my head and I don't plan to buy new speakers for the next 20 years. I will say that sometimes I wonder if I should have gone with the 228, even though I haven't heard one, simply due to ease of placement in my room. Based on what I have read on this forum, I think you would be ecstatic with the 228, especially if this is primarily for HT use. But even for music use I would assume the 228 is better than most speakers on the market at any price.
Good luck with your decision...the good news is you can't go wrong with either.