Audio Research SP9 MKII to MKIII Upgrade

Apparently ARC can also add a remote to the SP9 for about $700. Ouch!!!
More curiously though is how well the SP9 mkIII or modded version would compare to say a newer sp16 or the like. It seems as though modding or upgrading is really pricey and there are quite a few newer models available on Audiogon for less than the cost of the mods.
I'm asking because I am considering an SP9 myself.

Try listening to the amp with 7308 tubes instead of the stock 6DJ8. I'm using Gold Aero Platinum Grade Gold Pin on my Mk II.

One cheap mod that makes a big difference is using fast recovery diodes in the power supply.

I had the MKIII upgrade done a year ago. There is a noticable improvement in sound quality, that I believe was worth the $800 cost. While the advice to sell your MKII and buy a MKIII on Audiogon is economically sound, I should mention that ARC included a really nice screwdriver when they returned my upgraded SP-9!!!

There is an audio research sp-9 MKI for sale and would like an mkII or an MKIII , however is starting out with

a sp-9 mk 1 to a mkII worth it or go out and buy a mkII directly or sn MKIII?

First time here so Hello to everyone.