I have the $30 T-Mobile plan that I use on a few different phones. On the N4 it does not get LTE (obviously) but when I stick it into my HTC One Google Edition the LTE works perfectly. So I think the short answer is that T-Mobile does not do anything to block LTE on their prepaid plans, it may not be the same with other services however.
Update - I transferred my net10 sim from N4 to N5 and manually entered the exact same APN values and LTE worked. Speeds when I tested were at hspa 2 Mbps down and with LTE 12 Mbps down.
LTE signal indoors appears to be a lot weaker than hspa: 1-2 bars versus 4 bars. However even with 1 bar, LTE zips along just fine. Outside LTE is 4 bars.
What's kind of interesting is that you'll be at 1 bar with LTE and then you make a call or answer a call and the phone switches over to 4 bars. Voice must switch over to 3g.