BBx15 ESATA/SATA SSD performance compared to SD card

I have had my BBx15 for about a month or so. Very nice design.
I have made my share of blunders but am working through them.
Have installed Qt, PocketSphinx and can do a respectable job with off line speech recognition.
Am using 32GB SD card for now but am wondering if I will run into bottle necks as I install more
data to the card.

Am curious to the performance increase, if any, with an ESATA SSD setup over 32GB SD card.

Also any tips on installation from image changes, to preferred hardware.

Thank you!
Andy

laptop: 5400RPM:

[ 4.665845] ata1.00: ATA-8: Hitachi HCC543216A7A380, ES1OA60W, max UDMA/133

voodoo@b2-am57xx-beagle-x15-2gb:~$ sudo hdparm -tT /dev/sda

/dev/sda:
Timing cached reads: 2116 MB in 2.00 seconds = 1058.29 MB/sec
Timing buffered disk reads: 218 MB in 3.02 seconds = 72.23 MB/sec

el-cheapo: SU800

[ 2.525814] ata1.00: ATA-10: ADATA SU800, P0801C, max UDMA/133

voodoo@b7-am57xx-beagle-x15-2gb:~$ sudo hdparm -tT /dev/sda

/dev/sda:
Timing cached reads: 2100 MB in 2.00 seconds = 1050.25 MB/sec
Timing buffered disk reads: 766 MB in 3.00 seconds = 254.92 MB/sec

OnBoard eMMC:

voodoo@b1-am57xx-beagle-x15-2gb:~$ sudo hdparm -tT /dev/mmcblk1

/dev/mmcblk1:
Timing cached reads: 2114 MB in 2.00 seconds = 1057.33 MB/sec
Timing buffered disk reads: 234 MB in 3.00 seconds = 77.90 MB/sec

Regards,