Why no SSD's in TiVo's with TE4?Well the original poster was asking about an EDGE so pretty much everything I suggested was considering that. The 15mm will fit in an Edge but a really tight squeeze, cover may not close completely and have to leave out part of a bracket. A 2.5 9/9.5mm will fit but largest capacity 9/9.5 disk based CMR is 2TB I think. However they were also interested in 6TB and up, the 5TB 15mm 2.5 SMR drive is CLOSE but there is NO 2.5" disk based drive larger than 5TB. I will stick with my original recommendation, external, CMR 3.5, Sata to Sata (skip the Esata connecting to the enclosure), then can go as large as you want at least 14TB, maybe 20. It's not tough really, once you have the correct enclosure, cables, drive about 1/2 hour to an hour.
By the way, forget about SSD for an Edge, at least as far as I know. Edge is TE4 only. There are a few people testing large capacity SSDs in Tivos but TE3 ONLY. As far as I know no SSD will work with TE4 (if I am wrong, if anyone got one to work please post). So if true no SSDs in Edge, TE3 capable Tivos only.