Fusor Vacuum Pump Choice

I have been neglecting general education on vacuum pumps. So here is Technical Notes on Various Vacuum Pump Types. And of course the wiki on Vacuum Pumps. All for the purpose:

I'm trying to decide on a vacuum pump set up and have come up with two candidates based on their compression ratios for H2:

Adixen ATH31+. 1E11 N2, 1E5 H2 Compression Ratio
Aprox Prices:about $4,700 pump, about $1,700 controller, about $600 required accessories. 4 1/2" CF High Vacuum connection.

Pfeiffer TMU 071YP >1E11 N2, 1E5 H2 Compression Ratio
Aprox Pricesabout $5,200 pump, about $1,300 controller. 4 1/2" CF High Vacuum connection.

	l/s	CR	TU	Wt	IF	OF	FP	FPS	$Pmp	$Cnt
ATH 31+	14	1e5	5e-10	2.7	4.5" CF	KF16	45	1	$4,700	$1700
TMH071P	42	1e5	5e-10	8.4	4.5" CF	KF16	18	2.5	$5,208	$1,298

Abreviations:
l/s = Pump Speed in liters per second For H2
CR = Compression Ratio H2
TU = Ultimate pressure in mbar
Wt = weight lbs
IF = Input (High Vacuum) Flange
OF = Output (Fore Pump) Flange
FP = Max Foreline Pressure mbar
FPS = Min Foreline Pump Speed m^3/hr
$Pmp = Cost of the Pump
$Cnt = Cost of the Controller

The Pfeiffer looks like a better pump for the money. A lot will depend on the fore pump. I'm leaning to a roots blower or some other oil less type pump. So let us look at some. First some education: Scroll vs Rotary Lobe Pumps.

IDP-3, technical [pdf], dry scroll, 3 m³/hr rate, 2.5e-1 torr. ultimate, $2,650

ACP15, technical [pdf], rotary lobe, 14 m³/hr rate, 3.8e-2 torr. ultimate, $5,134

1 torr = 1.33 mbar