MBR -> GPT migration questions

[beaker%sdf.org@localhost (beaker)]

Hello,
I recently installed NetBSD 10.0/i386 on a mSATA SSD via an IDE/mSATA
adapter.  This SSD has an MBR partition table which I'd like to
migrate to the GPT scheme via the "migrate" option described in
gpt(8), however I'm not confident that I'm fully understanding this
and don't want to mess up what is currently a working system.

Some questions:
1) is MBR -> GPT migration as simple as running '$ gpt migrate /dev/rwd0'
   or is something else involved ?
2) is there any benefit to doing this migration ?
3) does my disc look like it meets the before & aft partitions space
   requirements (see below) ?

By the way, the drive is 128GB but I'm only making use of about
32GB, just a single NetBSD partition (no swap).

Regards,
-B

--
# drive info / current MBR scheme:

ituner: ~ $ atactl wd0 identify |head -n5
Model: SAMSUNG SSD PM851 mSATA 128GB, Rev: EXT49D0Q, Serial #:       S1EUNYAF817256
World Wide Name: 5002538844584D30
Device type: ATA, fixed
Capacity 128 Gbytes, 250069680 sectors, 512 bytes/sector
Cylinders: 16383, heads: 16, sec/track: 63

ituner: ~ $ gpt -r show wd0
GPT not found, displaying data from MBR.

      start       size  index  contents
          0          1         MBR
          1         63         Unused
         64   76566672      1  MBR part 169 (active)
   76566736  173502944         Unused

ituner: ~ $ disklabel wd0
# /dev/rwd0:
type: unknown
disk: sd
label: fictious
flags:
bytes/sector: 512
sectors/track: 63
tracks/cylinder: 16
sectors/cylinder: 1008
cylinders: 16383
total sectors: 250069680
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0		# microseconds
track-to-track seek: 0	# microseconds
drivedata: 0 

4 partitions:
#        size    offset     fstype [fsize bsize cpg/sgs]
 a:  76566528        64     4.2BSD      0     0     0  # (Cyl.      0*-  75958*)
 c:  76566672        64     unused      0     0        # (Cyl.      0*-  75959*)
 d: 250069680         0     unused      0     0        # (Cyl.      0 - 248084)